As a follow up to my original post:
I had the oil drained and refilled with PP 5W-20 by a mechanic that I trust. The oil that came out looked like it had been in use for several thousand miles. It was very dark brown and looked just like the stuff that had been sampled when the dealer "changed" the oil on Friday. I realize that oil color has no relation to how spent it is.
The oil that was put in yesterday looks much cleaner!!! I am happier. The mechanic also found a minor power steering hose leak - so that'll be fixed under warranty at another dealer.
I will probably change the oil myself next time. I'll buy some ramps and a strap wrench. My driveway was ruined a few years ago by a leaky old Town Car, so I'll change the oil over the same spot!
Thanks to all of you for your advice - I really appreciate it.