At first I thought that it was just my D5100. I have to straighten at least 75% of my photos. Since I moved up to a D7100, I'm finding the same thing. I don't use live view, so forget about the level in there. I line up to the grid in the viewfinder, and I still get pics skewed to the left (left if lower than the right) at least 2-3 degrees. No difference what lens I use. 18-140 or 35. Maybe I'm just to picky about it. Not sure. Anyone else have this happen?