You said, "she was roaming her tank looking for food". Then you reached in the tank. She mistook your hand for food. It happens. Someone replied that you will begin to recognize behavioral clues. I think thats part of the allure of ball pythons. Im not convinced that "cage aggression" is an appropriate term. They strike because they are hungry or because they are scared. They dont see a human any say,"I'm gonna bite the pee out of this One! They can become accustomed to eating at a certain time/schedule so it's up to us to recognize hunger/feeding behavior.:)