Yesterday within two hours I got texts from AT&T saying that I had used 65%, 95%, and then 100% of my monthly 2 gig data plan.  All I had done was listen to a couple songs and check facebook a couple times.  So i reset my data counter and checked in two hours later, and Spotify had used 365mb for just a few songs.  

I have music quality at 9/kbps

I have no playlists seleced for play offline

I have sync over cellular data off

This morning i deleted and redownloaded the app.  I reset my statistics, double checked normal quality and nothing was set to sync.  I played exactly 2 min of a song connected to my data plan, and spotify used 56.3MB.   

Any clue?....