Kevin, the line drives me nuts. But now that the grout has dried it's not as noticeable. We went with a light grey grout so it doesn't stand out as much as it did when I first grouted.
The first 3 rows were fine, and then all of a sudden we got off track somehow. The only way to keep everything straight was to deal with a slightly larger gap in that area. I kept trying to push them closer but I had to worry about 2 sides matching up (picture each square has diamonds on the left and top side) and if I moved it any closer, it didn't match with the top. So it would have thrown everything to the right off after that.