Well if you think about it you have to move a hungry snake to the feeding bin, then a snake that just ate (and probably is still in feeding mode) back to his/her cage. That that gives the snake 2 golden opportunities to bite you. Luckily the bite from a BP really isn't that bad, think bee sting.
The danger comes when the snake doesn't eat the rodent, and the rodent gets hungry, or feels threatened. The rodent can bite/scratch the snake, and if left long enough this can happen: http://ball-pythons.net/forums/showt...ghlight=lesson
If the snake has struck the rodent, it can still bite/scratch the snake. Always make sure that you know where the rodents teeth are and have something like a pencil or chopstick on hand to keep the rodent from biting the snake.
As has been previously mentioned, feeding your snake pre-killed or frozen thawed rodents is much safer.