It was this past weekend in the SF Bay Area (Emeryville in the East Bay). I saw a post on Audio Asylum (in the classical music sub-forum) from someone who attended on Friday:
https://www.audioasylum.com/audio/music/classical/messages/3/37122.html
This comment caught my attention:
I'd also estimate that close to 100% of the other attendees were even older than I am - and I'll be turning 75 in a couple of months. I saw only one attendee of the female persuasion, but, like the rest of us, she was a geezer too. (But I suspect that the average attendee age will go down tomorrow, as people are off work for the weekend.)