As everyone else has said, it sounds like a defensive strike. They do this when they are stressed. Stressors are everything from incorrect husbandry (care and housing etc for your animal) to overhandling, to other environmental factors your snake experiences. Young snakes are particularly prone to defensive striking and may act defensively simply because it is in their nature to be wary of large animals that may be percieved as predators.

Everyone here has given you suggestions on husbandry, because many people who come here for the first time have not been given good information for keeping ball pythons healthy and happy. Big box pet stores often give out incorrect or incomplete information regarding care for the various species they sell.

I heartily recommend you read over bp.net's care sheet on ball pythons:
http://www.ball-pythons.net/modules/...warticle&id=59

Welcome to bp.net!