Been noticing this for a couple months. When it's raining, the touch screen starts going mad, so I lock the screen (side note, the rain still somehow "swipes" the screen, but my fingers don't do squat, thanks for the non-lock lock). Later, after unlocking the screen and wiping it off, the touch sensitivity is essentially gone. If they work, taps are delayed by 10-15 seconds, and usually offset from the actual touch location. The only way to fix it is to stop the activity and power cycle the unit.
I don't know 100% how to reproduce it, but I imagine one tech, an edge 830, and a garden hose with a sprayer could figure this out...
