I've been reading all the issues here about the build qualities of this phone. Mine has a hair gap on the top and the screen also rises slightly at the top edge. I've decided that these were ok and happily used my phone with great care.
No I do not have a case, and neither did I use a case for my previous Samsung Infuse which I used 2 years without dropping it ever.
Today when I turned my One over, the camera glass was cracked! It looks like it got hit somewhere and just gave in. Seems pretty impossible as the rest of the phone is in perfect condition without a single scratch. I keep the phone in my pocket top down, screen facing inwards as I always have in the last few years.
This is so frustrating...I'm afraid if I get an exchange I'll end up with one or more of the several build issues that people have been seeing.