Message popped up at the top of the GeneratePress theme installation process. Perhaps it related to the theme that was about to be deleted to be replaced by GP. I had several installed to try them and only one active – I deleted all but the active one. Now there is just GP and TwentyFifteen as a fallback.
The next time I see something weird I will take a screenshot. I just now tried to duplicate the process by making TwentyFifteen active, deleting GP and reinstalling it but no weirdness happened.
I am beginning to think I have resident fairies in my machine … 🙂