UPDATE: Stayed at the dealer a full day ( 2 nights with a rental Traverse ). Turned out to be a bad parking brake lever assembly. They replaced it under warranty of course. They mentioned that the HDs have a problem with brake lining coming un bonded and freezing up the parking brake. So they checked that too. Nothing askew there. The mechanic was able to release lever with a long screwdriver before getting it into shop. All in all just an inconvenience. Hopefully this was an isolated incident and not turning out to be a widespread issue. I use my parking brake every day so I guess we'll see as the trucks get older what happens. My advice, If it doesn't release after the second attempt, STOP!!! and get it looked at.