ive been long-arm quilting for customers for 8 years now- i start off with tiny-in place (locking stitches) so the threads can be clipped at the quilt surface- once in a while i miss clipping one- i try to catch them all-
i would call him and ask if he locked the stitches- if it's ok to just clip them- or try one near an edge and see if it starts to (un-stitch) if it is secure you can just clip them