Looks like most of everyone is fairly accurate in their descriptions of pythons from the Morelia genera. Typically I've found most all young Morelia sp., to very nippy for the first year. A three foot JCP is still considered young, and would deffinately be a likely canidate for giving defensive bites. Even as adults, I do not feel these pythons are that trustworthy. You'll often hear them giving loud hisses of displeasure as you open their cages. I'd suggest using a snake hook or bent coat hanger to remove your python from it's cage, that'll eliminate the usual startled, defensive bite. When handling them, try not to wave your hand in front of their face, and keep your hands closer together when they start to crawl. I've seen it too many times, where they start to snap at anything that's warmblooded, and moves within striking distance from their face. You really shouldn't have a problem with biting if you make slower movements and help them feel secure and relaxed.
On the other hand, make sure they are well fed! Jungles have huge appetites! A deffensive bite is usually a very quick nip and release. If your pythons is holding on, it's more than likely hungry! I agree with the suggestion of feeding it more, and maybe outside of the cage untill the biting problem has subsided. If you snake is large enough to take rats, try it now. You'll want to get a Morelia sp. switched over to rats ASAP! They have a propensity for eating mice, rather than rats. Start them young, before you have a 6 footer on your hands that only eats mice!!