Ive been using my phone for the past 3 months now, i do see some chipping at the micro usb door, but thats about it and quite minor this far. On one occasion i even dropped it straight on the open usb door... It was bent, and all i had to do was take a plier and straightenit out... Apart from the dent theres nothing much worse and readily noticable.
i think this might be environmental, or as previously suggested, due to exposure to some sort of chemical... Are any of you living in a costal region? (i dont) Humidity might be a factor... Its just a thought as metals dont do too well on places with high humidity... And most of the chipping seems to bw happening around metalic parts(including the usb door)
It's has also something to do with moisture from your hands. Mine has been in the silicon case from day one and it's only chipping on the usb door and sim tray where the case is not protecting it.
It's fairly humid in Denmark where I live most of the year, but still
It seems to be some kind of coating that make the mat finish that is chipping away.