HTC 8x "Dirty Corners"

I bought my California Blue HTC 8x from a Microsoft store in Orlando, Florida about 3 weeks ago. For the first couple of weeks, while still in Florida, the phone looked great. After getting back to DC I took my phone out of my jacket pocket one day and noticed that all 4 corners had turned black. At first I thought it was dirt or a stain but after attempting to clean the corners it appears that something else has happened. Either there was some dye transfer from my dress pants or jacket pocket or the soft touch coating had rubbed off.

I spoke to HTC and while they wouldn't admit to it being an issue they offered to do a warranty repair/replacement. I am just curious if anyone else has experienced a similar issue to me.