I have been quilting for several years but i have a p roblem and was wondering if any one else has this problem. after i cut my pieces of fabric and sew them together,(If my block should be 12 1/2 unfinished), why are my blocks 12 1/4 unfinished?? I have checked my 1/4 seam and it is right on. I would say this happens about 95% of the time. Does this happen to anyone else?