What is claimed is:1. A radio node, comprising:a node or connector configured to communicatively couple to a network;an interface circuit, communicatively coupled to the node or connector, configured to communicate with a computer, wherein the interface circuit is configured to:provide, at a first transmit time during a first time interval corresponding to a first instance of a transmit expire time, a first instance of a keep-alive message addressed to the computer, wherein a given instance of the keep-alive message requests authorization to transmit in a granted portion of a spectrum;receive, at a receive time prior to the first instance of a transmit expire time, an instance of a keep-alive response associated with the computer, wherein the instance of the keep-alive response authorizes the radio node to transmit in the granted portion of the spectrum until a second instance of the transmit expire time has elapsed;determine, based at least in part on the receive time and the first instance of the transmit expire time, an updated transmit time, wherein the updated transmit time is temporally offset relative to a second transmit time during a second time window corresponding to the second instance of the transmit expire time; andprovide, at the updated transmit time, which is prior to the second instance of the transmit expire time, a second instance of the keep-alive message addressed to the computer.2. The radio node of claim 1, wherein the computer comprises a spectrum allocation server (SAS).3. The radio node of claim 1, wherein the spectrum comprises a band of frequencies associated with a Citizens Broadband Radio Service (CBRS).4. The radio node of claim 1, wherein the updated transmit time is determined based at least in part on a difference between the transmit expire time and the receive time.5. The radio node of claim 1, wherein the updated transmit time is determined based at least in part on the first transmit time.6. The radio node of claim 1, wherein the updated transmit time is determined based at least in part on a number of instances of the keep-alive message that were provided until the keep-alive response was received.7. The radio node of claim 1, wherein the updated transmit time is determined based at least in part on a previous occurrence in which no instance of the keep-alive response is received prior to a previous instance of the transmit expire time.8. The radio node of claim 1, wherein the updated transmit time precedes a start of the second time interval.9. The radio node of claim 1, wherein the given instance of the keep-alive message comprises a heartbeat request, the keep-alive response comprises a heartbeat response, and a given time interval comprises a heartbeat interval.10. The radio node of claim 1, wherein communication with the computer comprises wired communication.11. The radio node of claim 1, wherein the radio node comprises: an Evolved Node B (eNodeB), a Universal Mobile Telecommunications System (UMTS) NodeB and radio network controller (RNC), or a New Radio (NR) gNB or gNodeB.12. A non-transitory computer-readable storage medium for use in conjunction with a radio node, the computer-readable storage medium storing program instructions that, when executed by the radio node, cause the radio node to perform operations comprising:providing, at a first transmit time during a first time interval corresponding to a first instance of a transmit expire time, a first instance of a keep-alive message addressed to a computer, wherein a given instance of the keep-alive message requests authorization to transmit in a granted portion of a spectrum;receiving, at a receive time prior to the first instance of a transmit expire time, an instance of a keep-alive response associated with the computer, wherein the instance of the keep-alive response authorizes the radio node to transmit in the granted portion of the spectrum until a second instance of the transmit expire time has elapsed;determining, based at least in part on the receive time and the first instance of the transmit expire time, an updated transmit time, wherein the updated transmit time is temporally offset relative to a second transmit time during a second time window corresponding to the second instance of the transmit expire time; andproviding, at the updated transmit time, which is prior to the second instance of the transmit expire time, a second instance of the keep-alive message addressed to the computer.13. The non-transitory computer-readable storage medium of claim 12, wherein the computer comprises a spectrum allocation server (SAS) and the spectrum comprises a band of frequencies associated with a Citizens Broadband Radio Service (CBRS).14. The non-transitory computer-readable storage medium of claim 12, wherein the updated transmit time is determined based at least in part on a difference between the transmit expire time and the receive time.15. The non-transitory computer-readable storage medium of claim 12, wherein the updated transmit time is determined based at least in part on the first transmit time.16. The non-transitory computer-readable storage medium of claim 12, wherein the updated transmit time is determined based at least in part on a number of instances of the keep-alive message that were provided until the keep-alive response was received.17. The non-transitory computer-readable storage medium of claim 12, wherein the updated transmit time is determined based at least in part on a previous occurrence in which no instance of the keep-alive response is received prior to a previous instance of the transmit expire time.18. The non-transitory computer-readable storage medium of claim 12, wherein the updated transmit time precedes a start of the second time interval.19. A method for dynamically adjusting transmit times of instances of keep-alive messages to a computer, comprising:by a radio node:providing, at a first transmit time during a first time interval corresponding to a first instance of a transmit expire time, a first instance of a keep-alive message addressed to the computer, wherein a given instance of the keep-alive message requests authorization to transmit in a granted portion of a spectrum;receiving, at a receive time prior to the first instance of a transmit expire time, an instance of a keep-alive response associated with the computer, wherein the instance of the keep-alive response authorizes the radio node to transmit in the granted portion of the spectrum until a second instance of the transmit expire time has elapsed;determining, based at least in part on the receive time and the first instance of the transmit expire time, an updated transmit time, wherein the updated transmit time is temporally offset relative to a second transmit time during a second time window corresponding to the second instance of the transmit expire time; andproviding, at the updated transmit time, which is prior to the second instance of the transmit expire time, a second instance of the keep-alive message addressed to the computer.20. The method of claim 19, wherein the computer comprises a spectrum allocation server (SAS) and the spectrum comprises a band of frequencies associated with a Citizens Broadband Radio Service (CBRS).