Yes, it will 'wierd up'. Wash and dry flannel twice before piecing or using for backing. That way it won't shrink and distort the quilt. I bought a darling little girls quilt at a thrift store for $2 - I'm sure it was there because the flannel backing shrunk so much and distorted the quilt. Ironing brought it back in shape, but who wants to iron a quilt every time it's washed? It was in very good condition, so I don't think it was loved too much.