I think hes on the right track, but has the wrong reason. It more has to do with the molding process of the plastic cones they use. Anytime you have something molded, poured, injection molded, whatever it is, and you have a leg or attachment coming off of the opposite side you will get dimpling, a slight dip or spot in the plastic. There is nothing wrong with this, its just due to the way the stuff dries and anyone in industry knows its unavoidable, thats why most plastic products are textured, it helps to disguise these spots.