Karla, when I've had that problem it was because of the way the quilt was moving (or not moving) when I was free-motioning. It didn't do the same thing on a scrap because the scrap was moving without a problem, but when I put the quilt on it would sometimes hang because of the weight or getting caught a bit on the corner of my quilting table. It didn't seem to take much drag to mess things up. It got better when I watched the drag and stopped trying to sew backwards to catch spots I missed :-)
Edited to add: Just saw your post about the burr - if you cut an emery board in half or slightly thinner than half, you can usually file out those burrs. Glad to know you found out what it was!