But if this is the second time around, you might be looking at a stale image and your button presses really are going to the player because technically gpsapp isn't in control yet.

I checked this out today while I was out to lunch. The behavior was as follows:

First time entering GPSapp, worked fine.

Second time entering GPSapp, the map screen was updating, my speed was changing on the screen, everything seemed to be working correctly. It was not a stale image, it was tracking my correct location on the route. When I pressed the right button to zoom the map, it fast-forwarded the music instead.

So it's not a stale image, and GPSapp is working when the bug occurs.