I am also seeing this issue. Only get reboot notifications for my UPS and PBX equipment though. Never on Cisco equipment.
this happens to my Orion server as well. Its randon too. Sometimes I reboot the server, and no false alerts are sent. Other times, it sends out many alerts, saying that adevice has rebooted. The alert actually contains the correct reboot time of the device, but that time might have been months ago.
This happens on cisco switches. It doesnt seem to be issolated to a perticluar model. Although it did seem that most of tem were catOS switches. I cant remeber if there were IOS switches included in the alerts or not. It has not happened in a while.
I'm pretty sure I opened a ticket on this that was never resolved.