They do eat things weird from time to time, it's nothing to worry about.

Now that he is eating, the next meal should be okay to be a normal sized prey item. I think what other posters were trying to point out was that it is more common for a ball python to refuse to eat a meal that is too small than they are to keep rejecting an appropriate sized meal. It may be that the lady was offering him meals that were too small for quite some time.

-Jen