I think it has something to do with them maybe not being able to smell the difference between your hand and the rodent before it strikes ... but the sources I heard it from I can't call completely reliable so I don't know.
Let's just put it this way: big breeders feed inside the tubs, and as far as I know very few of them still bite. And this probably has to do with the snake, not the hand/rodent confusion.
MH
Who the hell is Pat?
"Pattimuss doesn't run, he prances most delicately, like a beautiful but sad fairy, winged and capped, curly toed shoes on each foot, dancing on dewdrops while lazy crickets play soft music for him to keep time by...." - Wes