Shhhh, the NSA is listening. LOL! Sorry, just kidding.
I have seen reports of this. It is reported to happen when you access Siri when you are connected to you car audio via bluetooth.
Make sure you are unpaired from your audio, then bring up Siri and then close her out.
You could also try a hard reset...hold the on/off button and home button down at the same time until the apple logo appears. Then release and wait for the phone to reboot.