This subject was just brought up a few weeks ago. If I remember correctly, most did not tip their long arm quilters unless it was for a really rush job or they did an exceptionally special job on the quilt. Most of the quilters on this board indicated that they did not expect to be tipped but it was a nice surprise when they were. I'll try to find that post & link it.
Found the link:
Tipping your Long Arm Quilter