Anyone Else Have Audio System Hiss?

I really like the audio system on the Prime, but I can't help but notice a low hiss when the car is turned on and not playing anything through the speakers. It goes away when the car is turned off so I'm sure it's not anything mechanical. I'm under the impression that the car's audio system is pretty much always on so it can play the startup and shutdown sounds and my feeling is that an audio cable somewhere may have been poorly secured and somehow got moved to a source of interference.

I'm wondering if anyone else has a similar issue.