Since upgrading to v10, I now have this odd behavior when I select the activity START button, or END (exit activity mode) button. My screen will just momentarily turn a very light, translucent white (sort of like flashlight mode). I don't recall it even doing that. I wanted to see if anyone else had seen this. It just flashes, and then goes away. Everything else seems normal.
And it's not the backlight. I have actually seen it more after enabling the backlight with the light button.
**UPDATE**
So just on a whim, I changed my watch face to a Garmin default, and it doesn't do it. So its my watch face... in case anyone else sees it.