Still playing my game as Italy, I have conquered Tunisia quite some time ago, but France recently had an event called "Opposition To The Franco-Tunisian Treaty Of Cooperation" (id 162666). It hasn't done me any harm and I don't think it will, but I still think it's weird this would fire when Tunisia doesn't exist. Apparently the event only occurs after a certain date in 1879 (which I just passed in my game) when one of two events (or both, as it's an OR trigger) has fired.
The first one is an Ottoman event about Franco-Tunisian Cooperation, so that makes sense. The second one however - the one that makes it possible the event triggered at me, as the other event certainly didn't trigger - is an event of British India, about the "Attack on the Fox". This all happened way back in 1852 and is part of an event chain in which British India takes over a part of Burma.
I fail to see any relevance between these two events and so I assume this must be a bug of some kind.