yes you are correct about that. I suppose my sequence just drifted that way.
I was a little set back on my heels when I saw what I thought was a lot of sequences similar to mine. http://www.familytreedna.com/public/ht35new/default.aspx?section=yresults
Mark Jost was kind enough to compare a haplotype group of about a dozen Murphys with sequences similar to mine. One of the Murphys is a 36/37 match.
It worked out to a common ancestor perhaps 825 years ago.
Maybe shortly before that a common ancestor of mine had a mutation to 393=12?