Here's one I haven't heard from before. I had to turn Touchless Control off. More than once, my phone just started "talking" and the screen was on Google Now. Somehow it thought I said "OK Google Now". I tried retraining it, no help. It has happened in my shirt pocket, sitting on the table behind my desk while I was on the phone, and once when I was watching TV. When I was on the phone, the person on the other end asked me who that was, and I said my phone just started talking to me.