Alternator is 8 years old - maybe 2500 miles on it? My fuel line doesn't run near the alternator as I have a totally non-stock carb/intake/spacer.

The only thing I can figure is that I was doing work under the hood to replace the fuel inlet fitting/filter/hard line and perhaps I bumped something and made a loose connection? I have no idea what it could have been as I looked at the two field wires, ground, and output connections on the alternator.

I did fire it up again and took it for a short drive. Per the ammeter, it's charging normally, even with the AC/blower motor on.

Of course when the car is heat soaked and then driven in 90+ degree heat, it likes to be finicky with idling but that's a whole other story.