TB had this happen with both the OTA GB update, and also now on BAMF Cubed ROM. Alarm is set for 5AM or whatever, and the next morning it doesn't go off, when you check the phone, the time on the phone itself is an hour behind. When you reboot it, then it corrects to the same time.
In time we have had the phone, since the week it came out, this has happened twice and both times have been since the GB OTA, but one of the times was on the new BAMF ROM.
Any idears? ANyone heard of this?