Suzeeq and Salmonmac - I squared the piece to the table under the towel. The second picture is hard to see folded but it really shows the difference. I thought the needle guide might help put it in perspective.
I checked my CO and BO and they match. I have never had a problem with the difference between my knitting and purling before so I'm leaning towards inadvertantly doing a half row which hadn't crossed my mind. The stitches are tiny and the black yarn was difficult to see even in the best of light. But if that's what I did, I must have done it more than once to get a .25 inch difference don't you think?