BB Bold 9000 :: Bedside Mode And / Or Standby Mode?

So earlier today before I went in to school I put my phone in bedside mode (so that the led would not blink (I use berrybuzz, which is very bright)) then locked the keyboard and put it in standby, for added security, before putting it in my book bag. After 2nd period I got my phone out and it was hot, as if it had been continuously downloading something or playing a video. The screen was dim but never turned off. The battery, which was at 100% only 1 or 2 hours earlier, was drained to 1 bar. I checked to see if any apps were running, with no luck, and then pulled the battery out and left it out until about an hour ago or so. The phone is fine now, but I don't know what happened.