he is just testing his boundaries to determine where he fits in the pack, remember the alpha dog eats first. you're definitly right, you got to nip it in the bud.

when my dog was a pup he did the same thing. my initial reaction was to pull back my hand, but then i thought about it and touched his bone again. when he bit me i slapped him on the head and yelled at him and repeated this process about 10-15 times before he quit biting ...never had a problem since.