Thanks for the great ideas already. Lots to check. I am running a generator.
Battery new last summer, and charging system was gone thru by a very good auto electrician then, because I was having VR issues and intermittent amp light condition, he got that sorted and said the gen was good at that point, maybe putting out a little on the high side but not an issue, I think he mentioned.
It might have been doing this all along but until I drove it in the dark this spring I hadn’t noticed it.
I can take it back to the shop and get his ideas too, but I thought I’d start with getting some ideas here!

Thanks again, everyone!