BPs typically arent very aggressive. They are nippy when theyre young and they are nippy when they are stressed, or provoked (poking him in the face). Accidental strikes can happen if youve been handling rodents and your hands smell like f00dz! But BPs are typically very docile and shy creatures. Young BPs outgrow their aggression as they get more comfortable with living in an enclosure and being provided food and what not. My het albino girl was nippy to her previous owners but she got over that quick once she had everything set up right for her and allowed time to adjust.
I don't believe in cage aggression. Sounds like he is just a little freaked out from the new environment and a big scary "predator" hovering over him and picking him up.
Don't sweat it. He will get over himself and realize you aren't going to eat him soon enough.