This makes no sense, can you figure it out?

My daily driver started having an odd but very loud buzzing in speakers. It's so loud I can't hear the proper sound from the speakers. The sound increases and decreases with the volume of the stereo. I found that if I pushed the dash panel face to one side or another the buzzing went away. Okay, the first thought is that something is causing electrical interference.

But here's the rub: the dash face piece is all plastic and it doesn't even touch the stereo unit! The facing piece (I've had it off many times) does have a small light in it that goes on and off with the dash lights and contains a pair of small metal clips that hold it to the main portion of the dash panel (which is also plastic at this location) and these clips are a good inch from the stereo. The stereo is bolted into the car with 4 good sized bolt/screws and does not move. The dash face is held in place with two small screws and two small clips and does have some movement but not enough to actually touch the (plastic) face of the stereo.

How in the heck could the position of a piece of plastic cause radio reception interference? I cannot stress the extremely small amount of movement of the dash face panel required to go from silence to loud buzzing. The only electrical connection associated with this panel is the dash light and since the light works the connection is in place and besides, that connection is 4 inches or more away from the stereo unit!

I plan to pull the dash face panel off tonight to take a look but I can't imagine that I'll find anything obvious. At least I can make the buzzing stop, until the next pothole makes it start again! I can make the sound come and go at will by moving the dash face piece so it certainly appears to be specific to the location of that dash face piece.