I made one of these rugs and mine did the same thing. I took out 5 rows. My machine is next to a wall and every time I went around, the rug would hang up on the wall and, unknowingly, I was forcing the seams. I have a huge sewing table that I used to quilt my quilts on. I got that out, finished the rug on it, and it looks nice now. You have to keep the rug on a level surface when you are sewing it together; otherwise, you will have a drag which may cause the rippling.