And you created an opportunity to improvise! One thing I like to do with quilt backs is put a strip of a fabric that is or some 'extra' (which means 'not quite right but arranged to look good')blocks from the top on one side. It saves me $$, uses the blocks, and, if the quilt is a small childs charity quilt, gives the child a more grown up alternative to the top as he or she grows up.