No, I can't believe any quilter would take such liberties. I'm not sure I would have paid her or at least not the full amount. But maybe you should have sewn the sheets together the size they needed to be for your top. By the way, you might want to consider not using sheets for your backs. They are not made/woven in a way the needle goes through the fabric the correctly (the needle can hit a fibers and break them and that can in time weaken your back and cause deterioration (that is what we have been told by fabric manufactuers).