My local reptile breeder will sell Chams after a month if they have reached a certain size. So only a select few get to leave if they have outgrown the rest of their clutchmates.
I have yet to see one at PetsMart but I would say that could explain small size too since PetsMart seems to struggle with some reptile care. The crested geckos always have a heat light on and are fed baby food, plus the humidity is always too low. Just not the best for the animals all the time.