This needs to be reported to the Postmaster General, they are most likely committing a felony and as long as they get away with it they will continue. It is sad to say there are many unscrupulous people in this world in all walks of life. We need to get back to the basics, "Thou shalt not steal" plus a few others. There are people who think they are owed all these things whether they are or aren't and most of the time they aren't for sure! I would send photographs of the carefully cut label to the postmaster General as well as contacting the local news media. Stir up as much media coverage as you can and maybe someone in the post office will do something. If they have security cameras it is a matter of going thru the tapes and most likely the people are too lazy to do so. Good luck in finding it, but I suspect it is gone forever. As someone suggested watch e-bay in that area and if you see it contact the authorities in that area as well as e-bay. Do you have a picture of your quilt. It is a good idea to take a picture of everyone of your quilts whether you think it is needed or not. You never know when you might need the evidence.