Spotify seems to be connecting and playing music off other people phones?

[luvshack5]

Hi all,

Random one here, when i am listening to Spotify in the house sometimes it will override my music and start playing music off another person's phone (not in the same house) It offers me a choice of "listen on this phone" or listen on "xpersons' iPhone) for example. Could it be something to do with the new Bluetooth headphones? 

Any help much appreciated! Don't much care for the music Bjorn listens to!