Please know you're not alone...I've had those days where I couldn't sew a straight seam to save my life. After ripping out the same seam for the third time, I just back away and come back a day or two later when my mind is fresh. Must have been a fluke for you that day. You can always say it's the same as those quilts where one block on the front is purposely turned or positioned the wrong way...except your's is the backing instead of the front. What the heck are those particular quilts called anyway? Somebody help out. :-)