Happens to mr with all announcements in the form of that type of pop-up (tick has passed message does it too)
Until this is fixed just refresh your browser and enter the world again, doesn't too long at all.
Oh yeah, as long as it's pop-ups it happens.
Better change the title and desc then
EDIT: Found a possible fix.
First, hold the button opposite the direction the screen is going. The screen should stop, but continue on when you let go. Now, tap the opposite direction button. It should stop! ^_^