EcoBoostJim,
Here is some helpful information about your mirrors. I've gone through this myself with my car, had it reprogrammed, and it has worked 100% for me. No more random clicking of either mirror.
1. The next time it happens, take a video of it on your phone. The dealer (some dealers anyway) will tell you they can't fix it if they can't reproduce it. Some dealers are more lenient than others but most will give you a hard time if they don't see it happening. With the video of it happening, you're covered.
2. When you call them up and schedule an appointment, they're going to need your vin number to see if this applies to your vehicle.
3. Tell them you want to schedule SSM 47835, which reprograms the module in the driver's door (DDM) and stops this issue on both the driver and passenger side. When they look up the "SSM codes list", the codes are not in numerical or alphabetical order on their screen so you may have to ask them to "look for it" a few times until they finally find it on their list of items.
Good luck, I hope you get it fixed like I was able to...