Tired to chew my hand

This happened to my son at a show in VA. I am a ball python man but picked up a blood out of curiosity, had an empty 20gal long at home. Got in the car and he took it out to look at it. Fine for about 2 minutes then it just opened his mouth and started gnawing on him! Never seen anything like it, no strike at all just chewing on him. Son said it did hurt pretty bad, he has been bitten plenty of times by balls. Blood everywhere!! I took it back and traded it and a little more cash for a Pastel! Reminds me why I am a ball python man.