Just got off the phone with Ron, the service manager at the local dealership (as posted earlier, the service writer wanted to wait till the manager got back from vacation).

He said they'd cover the MAFS, no problem, and booked an appointment!

And no, I didn't have to beg, whine, or threaten. Just asked politely.

Thank you Kelly Nissan, Beverly MA!!!

Incidentally, when I got the truck back from the diagnostic visit, they had cleared the code and the check engine light was off. It has since come back with the same code, but I still don't notice anything different in engine performance.
Might be puttin' out some nasty gases though - who knows.