Thought I'd chime in... I've heard that the black One's were supposed to be of the later builds so manufacturing processes should have been ironed out, well....
My first black one came out of the box looking like the lower right corner (looking at the face of the phone) had the black anodized finish rubbed off. They didn't have anymore so ATT ordered me another and let me use it until they came in. I then noticed on the same one the glass was higher in the upper right corner. You could actually catch your fingernail on the edge. The other corners were flush. Needless to say glad I wasn't keeping this one.
Rep calls and says your new phone is here. We went through three until we found one that didn't have some janky quirk to it. One had the emblems on the back completely crooked like Stevie Wonder was working that day, another had paint chips missing on the lower speaker grill, finally the last one was clean. The manager was very cool about it and brought out a stack of them.
I think looking at anything that close and you're bound to find imperfections. I have seen brand new Iphones with chips in the edges, S4's with uneven gaps in the plastic around the screen. I guess we can all be a little OCD when it come to something we stare at all day!