After your being a loyal cust. for so long,that alone,especially being a mil .miler would give you some weight.
Other than that,did you use anything related to UA that would/could count as UA miles(credit card(which is what I use at the present) car rentals,hotel stays or anything else UA recognizes as earning points.It could be eating out,sending flowers and a dozen other things.Go through your files to find ANYTHING that would have earned miles whether you signed up or not.