Is it just me or was the entire forum down all day yesterday? Anyone know what's causing this and if it'll happen again?
It was just a brief downtime that happened for quite a short while. I was caught as well, but I don't think everyone else will notice that. I'm not sure how this happened either but I can't guarantee that this won't happen again sometime during the next few years. The administrators know better than me when it comes to downtimes.

It's probably best to just ignore them and move on.
I saw it, too. I figured that it was just a server or database crash or something of that nature, and came back once it was over.