Semi-random songs added randomly to playlist [bug]

[Klesus]

So I've come across this one weird bug, I opened up a playlist I created recently and oddly enough new songs had been added in the middle of the playlist that I haven't added myself. And it's a private playlist. I say semi-random songs because there were only songs from other playlists, starred songs or songs added to my collection. I do not know what caused this bug. My only usage recently has been listening to playlists.

I'm using the spotify webplayer on firefox 39, windows 7 64bit. I doubt that has any relevance to the cause, but now you know.

Curious if there's anyone else having experienced the same issue or if this is an isolated case.