This has happened several times: When I put a quilt on my longarm, I tend to put it too close to one side of the backing. Then I hit the clamps when I get to that side of the quilt, so I take the clamp off, and pull the backing by hand to try to keep it taut. Lots of times, I end up with a pleat in the backing, so I have to take the quilt off and "frog" the stitching. Aww, nuts!