Ï've had that with my scrapshirtquilt. When you use different fabric (light and more heavyweight), they tend to get curvy and crooked. I tried to iron them with starch into the form I more or less wanted. some of them turned out ok. the rest I pulled while sewing and the very rest just stayed the way they wanted. I'll post a picture when that quilt is done, needs some back as well as quilting.