After you take out your stitching, I always need to remind myself to just slow down. Not sure if that might help you? The walking foot is feeding the top fabric through, the feed dogs move the backing through....and they need to work a little harder to keep the batting sandwich all going through at the same time. I also keep my hands right next to where I'm stitching and kind of smooth the fabric to the side as I go along. It's worth fixing, you don't want a bunch up on a lovely cuddly quilt.