When you take your quilt to your Long Arm quilter there are the usual items to tick off your check list: the backing and batting need to be larger than the quilt top by 3 or 4 inches on EACH side; quilt top has been ironed; threads on quilt top have been clipped.
One step which is often overlooked is securing seams which extend to the edge of the quilt. These seams often haven't been back stitched which means any slight tension causes them to begin splaying during loading.
A few stitches across the seam will stop it from unraveling or splaying (see photo below). If you have pieced borders you may like to sew around the whole perimeter of the quilt top using a small stitch, close to the quilt edge. Just be sure your tension isn't tight enough to cause gathering along the edge.
There is no doubt that your long arm quilter will be grateful and you will be happy with the result.