I took my iphone out of the case today and noticed black around the headphone jack. It happened a ring in the shape of the cutout from the case I use. Its a rubber case, so I don't understand how it left that there. I couldn't rub it off with cleaner either. It looks like my case had either stained the metal or scratched it. I looked around the rest of the metal and noticed more little marks. It isn't serious, but it leads me to believe that the iphone's metal band isn't as strong as I would have hoped. Any one else having that sort of issue?