In Game #99903785, twice after my opponents played a Fool, the graphic from the last resolved of the three Boons remained on my screen the rest of the game. You could move them aside, but the more recent of them kept moving back to the center of the screen. Very annoying.
Thanks for the report!
This behaviour has been observed a few times (but rarely), it isn't clear what exactly are the circumstances that causes it.
Conversely I find that the boon often doesn't get displayed when my opponent plays the card (I can't remember its name) that gives a boon that all opponents can choose to take under certain circumstances. I find myself having to view the kingdom to find out what the boon I am being offered does. Sometimes, however, the boon does get displayed. I've yet to spot any pattern to when it does or does not get shown.