I have not noticed this behavior, although most of the time I have my audio source set to Phone. But I did switch over to Slacker for a day or so and then back, and it's been working fine. What does your audio source get set to that you have to change it?
The somewhat recent (several months now) behavior I've noticed is that I used to be able to hit the area where the album art appears to bring up the audio source selection, but that no longer works. Now I have to raise the audio shade/window to the middle height to get the audio source selector menu to appear to change sources.