So the reboot loop has 2 causes. as told to me ny the sprint tech
1) cpu overheats and the phone reboots to save from any more damage say exploding battery
did you notice your battery really hot when it happened
2) bad line of code that it gets stuck in. Think a endless for/next loop
if either of those two you are SOL and we need a trip to the sprint store. If you are lucky , like I was, you get another device. Woot!!
if not well I hope you paid for the insurance