Yes I have had fabrics shrink, in fact I was working with a fabric I got at Wal-Mart that shrunk every time I ironed it. I know it was 100% cotton because I have spotted it on some sites being used in tutorials. I did prewash, it faded badly and then ironed before cutting. At first I wondered what I was doing wrong, maybe cutting mistake even though I slowed down and was so careful. After ironing I measured and sure enough every time I ironed it got a little smaller.