Some blamed the sharp edge for the phenomenon, but regardless of the reason, the Micro Arc Oxidation method might make the frame stronger than stainless steel, but the coating is apparently not as sticky as it should be on some units.
HTC now stepped up to its part of the deal, saying that "The finish on the One S was laboratory tested as being at a hardness similar to ceramic. While that's hard, it doesn't mean it's impossible to damage."
Just to be safe, HTC says that the any units out there that exhibit the chipped coating, can be returned in stores within 30 days, or whatever the period in your country is, or if that period has passed, it will just be fixed under the standard warranty procedure. Oh, the teething problems with new materials. Still, we'd rather have phone makers experiment a little than play it safe with the standard boring chassis.