The board briefly flipped to “Read-Only Mode” and logged me out for a little while there. Why?
I have no idea what happened, but the same thing happened to me.
Coup attempt.
In all seriousness I didn’t notice the read-only part but I did get mysteriously logged out.
Similar to the big mass iPhone Facebook log out of this past Friday?
I’ve had it happen to me a couple of times in the past month or so. Again, only for a minute or two. Glitch in the Matrix. 
I was away for a a while on other tabs, and when I went back, I had a little pop-up “You have logged out”. After I closed it, I was auto-logged in again, without having to type my credentials. First time that happened, yeah, a minor glitch, I guess.
An outage of this duration is a first-time for me, but I do recall being mysteriously logged out once or twice before, and then the site came back almost immediately. This time it lasted for something like ten or fifteen minutes, I think.
This needs to be fixed or some of us might soon long for the days when all we had to endure was extreme slowdowns of the old vBulletin site!
Strange: now I got a notification in the notification area of Windows 10 that someone posted to this thread, though I had turned off notifications for this site in preferences. Have to check that setting, but something’s not quite right with the board.
ETA: I checked my preferences, and yes, notifications were enabled. I had to disable them again.
It wasn’t a coup!
Temporal Time Skip. These are more common these days because of 5G.
It was just gas, I swear!
In the past couple days I’ve found that if I walk away for more than (I’d guess) five minutes, the screen is frozen by the time I get back, and last night when I tried to click my way out of it, I got a message saying that Discourse has determined that I’ve been doing too much of that darned clicking and that I should try to log back in later, which I wasn’t able to, for about a good hour.
@codinghorror replied about this to my related thread in the Site Feedback forum (which is the forum I think he checks most often).
So it seems it was a load issue, and they’ll be fixing it soon by upgrading our (virtual) server.
It’s us isn’t it? It’s okay, you can say it!
Could it be those rapid fire election/politics threads maybe?
Maybe Discourse is intended for smaller usage than what we’re using?
It’s kind of starting to lag a lot when it loads pages and stuff.
Antifa.