This is extremely common when a song resonates with listeners on an organic placement.
This is due to listeners of your music "adding" your song to their own personal playlists which is one of the ways users can save your song for later enjoyment.
Even a single high quality playlist can trigger hundreds of "Playlists Ads" and can be tracked inside your Spotify for Artists portal.
You can clearly see in the analytics the bump in playlist "adds" correlating to the campaign start date of September 19:
If this happens, that is a good indicator that your song is resonating with listeners and is inspiring a positive reaction.
All you need to do is pat yourself on the back! Great work on writing a great song!