PetCo's policy is to feed baby corn snakes pinkies once a week. My guess is either the crickets climbed in there from another enclosure (those enclosures generally have small gaps in them, making it easy for crickets to do this) or someone accidentally put the crickets in there while doing morning feedings. I'd mention it to a manager. It wouldn't surprise me if an employee was dropping crickets in their enclosure who didn't know any better.