Yeah, I don't know where Southwest contracts to paint, but there are a lot of places in that general area it could go to.
If they're just switching all 737 flights to SWA flight numbers on 12/01, I don't think they'll spend the extra $$ to change the seating configuration until the aircraft is scheduled for the changeover. I'm betting they've scheduled those as close to regular MX checks as possible for the changeovers as well....