2003 RR HSE - While riding down the road every once in a while I will hear a low toned beep in the speakers. I usually either have the radio or a cd playing when it happens. I rarely drive without listening to anything so I don't know if the volume of the beep changes with the volume of what i'm listening to. Has anyone else experienced this? I'm not using GPS when it occurs. Not sure if it would still occur while using GPS.