She could also have run into something. I find though, regular mollies do tend to be more aggressive, and head on with their attacks, or even sneak attacks. Are her fins tattered at all? How many females do you have, how many males do you have, and what size of tank?
Breed for the breed, not for the money; the words any REAL breeder would understand.
You must know nothing in order to know all, for all is nothing and nothing is for all.