I generally run over Bluetooth too, often in the car, and sometimes with Google maps as well. I continue to get the frequent crashes message (as above) and suspect this probably relates.
Often the phone is overheated from a short session in the car, although I also agree with @mackid1993 that the usage can happen in the idle period following (less so I think since changing the battery policy for the app, though i believe this breaks smart downloads).
Edit: @michael Here’s an example of today’s activity - not sure if this is normal usage for a couple of hour’s music or not 
seems high to me but will watch for higher…and keep an eye on background.
