This same issue has occurred also with my old phone, the LG G4 so I'm not sure if it's an LG thing or something. Sometimes when I plug my earbuds into the phone, the google voice app will open up and it will say something like "do so and so to use your headset while the screen is locked" I still never found out the reason behind this but it got to the point where I was barely able to listen to music without this popping up and interrupting. It got to the point where I had to disable the app itself to keep it from popping up all the time. Does anyone know any other way to stop this issue? I really didn't expect it to happen on this phone as well.