Flew SFO-JFK last week, there were only two BE seats showing availably for UG list at gate, 17 folks on list. Gratefully, I got the first seat, and to my GREAT surprise, about 10-15 minutes before departure, a delta employee (wearing civilian clothes but sporting a badge hanging around her neck) took the other open seat. I was shocked - there were at least a few other diamonds on the list after me, followed by other medallions. Is this practice permissible? I don't know if the DM's who weren't upgraded saw her get on and take the seat, but if it were me, I'd have said something. But it got me wondering, perhaps its their policy. Anyone know?