Funny, I had a [slightly] similar thing happen to me a few months ago. A 2 night reservation for a certain SPG property in Rome suddenly appeared in my upcoming stays, and after cancelling it twice, I left it to see what would happen. Still not sure, only that I got the stay credit and points and still have no idea how or what it may have been.
I have stayed in the hotel once or twice in the past but there was no unauthorized charge on my cc so I simply enjoyed the free points.