That may be but it sure sounds like a HD. I though it was reading the USB stick and copying files to the HD. Also the sound is closer to the display.

I based the above on the following from the owners manual, p189.
After connecting for the first time, the information...USB device are transferred to the vehicle...The information of up to four USB devices or for a total of approx. 20,000 tracks can be stored in the vehicle

I'd have to take out the Nav DVD and see if I hear it. Your probably right.