It doesn't look like an error to me. It looks planned. Who made the rule that every border/ sashing had to be the same width? If there is such a rule, I've broken it many times because I wanted to make a quilt longer than it was wide. Your quilt is lovely and I know you will be happy to have it hanging on your wall! However, if fear of the quilt police was the real reason for deciding not to donate it, my advice is: "GET OVER IT!" froggyintexas