Well, this happened.
I talked to the spinner guy in Grotto, who told me that I already span today (I had).
Then I asked to buy bombs from the guy (also in grotto) who sells them for 8 Gralats a pack. The 'buy/cancel' screen came up with the bombs, and when i tapped the buttons nothing happened.
At first the pop up purchase menu didn't disappear at all. I answered some pm's, thinking that it was just laggy, and the background of the purchase pop up vanished, leaving me with these buttons on screen.
Edit: After unsticking, the buttons are still present. When I logged out and logged in again, they disappeared. I went back and went through the same process again (talk to spinner guy, then go to buy bombs) and have the same issue.