I-Phone 3GS I-POD Default despite running other Audio App

I have the new Apple Iphone 3GS with latest updated firmware. I know this is really an Iphone issue and not a Toyota issue but this is annoying.

Everytime I press BT on the Prius Audio the Iphone defaults and starts playing recording from my IPOD App recorded music. This will happen even if I am already running Pandora, Slacker Radio or ooTunes. I then have to quit my other App, go into trhe Ipod App and stop playing my saved song. Close out of Ipod App, then restart my other Pandora, Slacker or 00Tunes. It's not a big deal but some what clunky.