This is starting to make some eerie sense. About a month ago I noticed my main monitor wasn't waking up from standby, though I don't let my PC itself go to sleep, just the monitors (in advanced power options: Display -> Turn off display after = 60 minutes). I disabled that and just use a screen saver and it hasn't done this since. That said, I never saw the NVidia driver events you're seeing, so it may be unrelated.

Incidentally, I'm on a 36x.xx driver, EVGA 980 Ti, MSI motherboard, displayport main monitor and DVI secondary monitor. I've been letting the GeForce Experience update as desired.