Ok.. Congrats on the little guy first off. Secondly, don't just reach in and "pet" him. This is just going to annoy him. You are messing with him inside his den.. You need to just reach in and quickly scoop him up. Do not go in towards his face. Scoop from behind his head near the end of his body. If he follows your hand when you reach in then cover his head with a small towel or something, then scoop.

Let his home be where he feels safe. If he thinks something is just going to keep reaching in and touching him, he may go off feed.

Snakes are not the kind of animal you pet like a dog or cat. Once you have him out, just let him crawl through your hands. If he keeps tracking your movements then just be sure to keep moving your hands under him and turn him so his head is pointing away from you.

This is normal for a young BP. With handling he will stop nipping at you. Once you know how to pick him up and handle him, you won't get bit even if he is still nervous about it.