This morning when I booted the machine it was back to normal.
The only thing I can think of that might have provoked this episode was that I ran pkgtool --> Setup --> services, and it's not transparent what that does. But the display isn't a service, is it?
I mention this because a few people have posted about persistent problems with fonts, and maybe that's what they were seeing. It reminded me of my attempts to install Slackware and Arch, where configuring the display is left as an exercise for the user
