In recent days I've encountered two or three, all between 11 and 11:30 PM Pacific time and all consistent with the system being busy doing backups and other housekeeping.

Part of the reason I didn't see them before may be that I haven't been on much during that time, or been writing something long that didn't require anything from the server till I was ready to preview or submit it.

I'm not talking about 12-minute delays now. I wouldn't even notice a delay unless it was 15 seconds or more, and I don't remember having to retry even for a full minute.