Heard of it. There's a thread here on TMC about one or two people that had it happen. I think it was reported about 1-2 years ago. I think the SC folks fixed it. You'll need to search the forum under the Model S section to find the thread.
And more than 2 years ago there was an owner on the TM forum that kept finding his rear hatch open. It happened to him over two or three days. He'd come out and find the liftgate open. Lots of discussion on this one. Bottom line? It turned out that he had bought one of those first leather fob cases. It used a snap on the top to hold the cover over the top of the fob. The owner carried it in his (tight) jeans pocket and when he sat down, the button pushed a little too hard down on the back of the fob and the liftgate opened. His own fix was to stop using the leather fob case. Funny how something so simple caused him so much paranoia. He speculated that someone had hacked his account and was using the app to mess with him.