It's really hard to tell without knowing more about the snake. My snakes around that age would want another mouse if it is a normal sized mouse. If you have another one give it to her and see if she takes it. If she does you may want to bump up the prey size a bit or feed every five days until the animal "catches up" from its time at the pet store.
You should really try to get the animal eating rats while it is so willing to feed. Rats are much easier in the long run.
Well I did see some small rats at the pet store, but they looked HUGE! Although, I guess i'm not a snake.