Notification is stuck on lock screen (iOS 6, iPhone 5)

I installed a program called Belly -- which is a sort of universal "rewards" card that lots of small stores can use. One of the features of the app is that when you are near a store that uses the Belly system, it will pop up a notice on your lock screen. This was actually a problem for me because I work right across the street from one such store, so the message was literally on my lock screen every time I used the phone, which got really annoying after a while. So I went in to the Notifications settings and turned off Lock Screen messages for the Belly app.

The message is still there. Huh.

Now I've not only turned off all notifications for that app, but I've even gone so far as to delete the app from the phone and reboot the phone. No dice. That stupid "Check in with Belly" message is still parked on my lock screen.

How can an app put a message on my screen when the app isn't even on the phone any longer?? Is there some sort of message cache in the phone OS that I can clear? How do I get rid of this???