Can you explain your setup more? How are you measuring temps, what are the temps, is your UTH regulated with a thermostat, etc
It's not unusual for BPs to not leave their hide, that's what they do. If they're roaming that usually isn't a good thing: it means they're stressed or hungry. A hiding BP is (usually) a happy BP.
He's probably very defensive because you just got him and he needs to acclimate to all his new surroundings. Give him a week with no handling so he can de-stress.
How soon did you handle him after he ate and for how long?