I always say,"It is your quilt, your creation". How does someone know it is a mistake? Maybe you planned it that way. I have a friend who is a perfectionist. She looses sleep if every seam doesn't match up exactly.I don't think she enjoys quilting because she is so perfect. I always tell her this. I do agree with others above, if you can't say something nice, don't say anything. I don't think someone would ask for advice/opinions if they didn't mean it. Don't get critical. Quilting should be something we enjoy doing.