If a snake bites you in the pet store, should you not consider buying it?

Were you holding other snakes? King snakes are highly cannibalistic and won't hesitate to eat another snake and will bite you if they smell snake on your hands. Nonetheless, the behavior you described was normal for a young king snake, which was actually a California king snake. "Banana" just describes a morph of California king snake. Babies are often skittish and can easily be tamed down.