You're right and normally he does

Usually whenever he had to cancel a daily, he did mention it on twitter and facebook. Perhaps this time it was just an oversight?
As for the indicator in the upper right corner, there is normally a countdown to the next show. Right now, when clicking on "home" it says "November: nothing on the horizon", so there are no shows scheduled right now. Of course this is also not 100% accurate, as sometimes a show takes place, even when it wasn't announced.
However, when the system works, then the shows are listed there and typically Sean also announces whenever there is a change, like when he took a one and a half week break recently.