Yeah, that didn’t make sense to me either. I was trying different things to see what works...
So... the screen saver came back for me the other, but I noticed something else. I had left my AppleTV while I was watching cable TV and the screen saver came on. It didn’t come back after turning off the AppleTV.
I’m obviously speculating here, but I think other input sources that you normally leave on for a while, such as a pc or gaming console, might trigger the screen saver if they’re sitting idle. We might be getting closer to solving the mystery