Opening web player causes Android app to start playing

[Ithuvanian]

Earlier today I was listening to Spotify on my Android, and I left the app open when I was done. Then, several hours later I logged into Spotify web player on my laptop (with headphones, because I was in a public place), and my *phone* spontaneously starts blaring the song I had been listening to earlier.

Is this a bug, or is there some setting that will prevent this behavior? Ideally I would like to completely prevent my phone from controlling play on my laptop and vice versa; it's more of a nuisance than a feature.