iPhone 4S Bluetooth Question

[Suzannesstud]

I have Bluetooth set up on my new iPhone 4S CDMA on Sprint with my Kia Forte which has Bluetooth built into the radio. I am noticing that after a while, maybe 30 minutes or so, if I make or receive a call, my Bluetooth is no longer connected, and I have to reconnect either by doing it from the radio or by doing it from the iPhone 4S and it then works again for a while. Both are still paired when this happens. As far as I can tell, this is acting like the connection somehow times out if I don't make or receive a call for at least 30 minutes. Is there a setting somewhere I need to change or is this what should normally happen?