I noticed that on my Friend Activity, I could see a friend listening to a song from a playlist that's apparently set to private.

I first thought it was the name of the album but when I clicked on it, it showed a playlist that my friend had made. However, she does not have that playlist in her Public Playlists page. I'm guessing if a playlist that's created by you is not on your Public Playlists list, it must have been set to private. 

It certainly is a problem that your live activity reveals your private playlist. The only solution to this as far as I know is for an individual to go into Private Session mode, but it would be much nicer if your activity through a private playlist would only reveal the name of the album and not the playlist itself. 

Did anyone else experience this issue of having their private playlist followed by other people/ or the hunch that you're following a private playlist? Is it possible that a playlist could be public but not on the Public Playlists page?