I've just built a system with Xubuntu 13.04 and it's continually (~ every 15 minutes) asking if I want to upgrade to 13.10. I hit the "Don't Upgrade" button and it's back again in 15 minutes or so. Same with the "Ask me later" button.
It's asking this in a small box that can't be expanded and won't let me see the whole thing even with the sliders.