android phone music player issue

Recently changed my android phone and have a really annoying issue - the phone pairs with the vRS and works with no problem via bluetooth. the issue happens when i leave the car - switching off the ignition somehow switches on the music player on the phone in my pocket. it happened intermittantly with my last android phone, but now on nearly every occasion - any ideas how to stop it from happening? tried looking through my phone settings and haven't found anything