Magic December 1st Reboot

I notice that two of my Vera’s (not sure about the 3rd because internet access is down) restarted the MiOS system at just after midnight (local time) on the 1st of December.

At first I thought it must be a power outage in the community that hit both of them, but when I checked it was only the MiOS system that had restarted with an exit code of 0.

So I have to ask, why does this happen? Will MiOS restart at midnight on the the first of every month?

I am not entirely thrilled by random reboots of the system as I might well be doing something that relies upon global Lua variables. For example I could have switched something on for 10 minutes, but a reboot in the middle of that would mean it didn’t shut off again.

I accept that there can be random failures that cause similar problems, but there is no obvious excuse for it being done deliberately without any warning! If these automatic reboots are documented can somebody point me to where?