Hi. I have a Samsung A5 (2016) and it has the same problem.
So, first conclusion: we are not experiencing a problem on x series of x model, because I read comments about people using S6, S6 edge, Note 4, A5, etc.
Then, we are making focus on the Gear VR app but that's not the real point, because I've disabled the app with the Package Disabler and now I have the "same" problem with other apps. The phone "feels" something is plugged into the USB port, a VR device, a battery power sharing cable, a dock, a power charger, etc. Second conclusion: When we disable an app with the Package Disabler we are just hidding the apps wich react when we plug (realy or not) something in the USB port. So we do not see the pop ups, but the problem is not fixed.
So, we realize the problem is related with the USB port. Now, the BIG QUESTION: Is it a software bug? Or have we all physically damaged the USB port?
What I think: If it were a problem with x series of x phone I'd say it's a factory problem. I'd say the phone is not well produced. But when I find people from all over the world experiencing the same problem with different devices from the same brand (Samsung), I'd incline the problem is hosted in the software. But in the other hand we can not say it's the OS (Android), because we have the same OS as other cell phones (Hauwei, LG, Motorola, etc) wich have not this problem. And also in my case I've been using the phone for two months perfectly and one day to an other it started failing. Finally we have two alternatives, a Samung app (may be gear VR or other) has been updated and even if we disable it, now the phone is "infected" with the bug and "feels" it's been plugged into a dock, or somehing; or we have really damaged the USB port because we're not careful or because it's not well manufactured by Samgung.
Franco, from Argentina (Samsung A5 (2016) bought in the US).