Could just be an unfriendly snake. A friend of mine has a BP he's had since it was a hatchling and handles it all the time, and it still (5 years later) acts like it's got to kill everything.

But yeah, most likely a handling issue. Try hooking him out of his enclosure before handling him? Maybe when you reach in you trigger the feeding response and it's just a really strong one. I had an old BCC that acted like that, unless you let him come out on his own or used a hook. Same case with him, always handled from day one but even 20 years later (He belonged to a friend of the parents) he was still aggressive unless you let him know somehow it wasn't feeding time.