After the most recent Spotify update and the white design appeared it became possible to follow artists and users. I was automatically following some of my "most played" artists (according to Spotify anyway) and a single user.
This user was followed by many people, so it wasn't a coincidence. I think he had around 30 followers at that point, while the rest mostly had zero or at most a couple. I immediately stopped following him. Now a total of 113 people are following him! I'm guessing this is due to more people updating to the newest version and automatically following him, just like happened to me.
What is causing this? Is this a random bug or has this user done something to force people to follow his user automatically? The thing is that this guy is not some "random friend", but rather cynical, and probably the only friend on my contact list who would read about how to or even pay for getting people to follow him.