Min has been rebooting sometimes several times a day for about the last week and a half. There is a new update out, but I don't think it addresses the reboot.
Call Verizon and let them know. My wife had random reboots for awhile and we called them and they said that there wasn't an alert out for that issue. They told us to take the battery out or restart it because it is like a little computer and the phone is telling you it needs to reboot when it does that. Of course that's a load of crap and they don't know what they are talking about.
So call them if you are really having issues. My wife hasn't been having that many issues recently, but it's still worthwile to call.
mine just did it about a minute ago that makes 5 times today! a quick well not really quick is remove the battery put it in the freezer and put the phone in the fridge both for about 30 minutes and it should work until the next time and if your revo is running hot all the time like mined does and lags/freezes up this is a good way to cool it down and your phone will work like new for an hour or two.