Here are my four corners. I had the phone for 2 weeks in Florida and kept it in jean pockets with no issue. I got back to DC and started putting the phone in my dress pants and winter jacket breast pocket and about a week later I noticed the corners. It's almost like they all happened simultaneously. I have contacted HTC via their website and will update the post with their comments.
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UPDATE: HTC contacted me within an hour of sending in the original email via their website. The technician said he had heard some other cases of discoloration and offered a warranty repair/replacement. For me this is a secondary phone so it was not an issue to work through the repair process. I will be sending the phone in and he said they would likely just replace the cover and send it back to me. He did not acknowledge this as being a widespread issue but he did say that he had read some peoples posts regarding the discoloration. He said it was possible the coating was not evenly applied to the phone and that was causing the issues in the corners. He said he has tested the AT&T and Verizon versions of the 8X and he has not seen the discoloration in person. He claims to keep the phone in his jean pockets without a case and had had no issue with the discoloration.