Talked to the wife again...this is more confusing.
I think it is possible, but maybe not likely, that while she was watching netflix that morning, the remote might have been bumped, which could have started playback. It would have had to have been bumped again, with the back button maybe or similar...my remote is RF, so it is certainly plausible. (just FYI, I thought she worked that morning, but I was wrong, so she was home, but insists that she didn't watch any live TV, only netflix via the TV app).
What I am going to do, is add a cntrl-s (stop command) to the remote any time the back button is pressed...just to be sure that isn't what is causing the problems. I can't think of a reason that I would use the back button where I would want playback to continue.