This is a BOM club block from my LQS that I am audtioning in scrap fabric. As a novice, I was very careful in my cutting, seam allowances, and pressing. But the strips hoizontally are 1/4" short.but the vertical length (joined strips) is the correct 13". Why would the block be perfect one direction, but not the other? Please help me understand what I did wrong before I cut into my good fabric. Thanks.