My grandmother always told me that some quilters make a mistake on purpose and may flip a block, or make a slight change in a star, or put one block the reverse of all the others. She said it was the signature of many quilt makers. However, I am 64 and that was a long time ago but I always tell anyone who finds a glaring (usually the quilt maker is the only one who notices) that "they are so lucky to get "one of a Kind" quilt" however, most people never see it. Just enjoy the accomplishment and learn from the error. Or start making that your "signature". :-D