I just check IPD..
Does not seem to be the problem.
And closing one eye, distortion remains.
But, there is no distortion in simple 360 videos, only in 180s !! (tried my:-Experience the Blue Angels in 360-degree video-)
Since 360 use all the space there can be no distortion.
In 180s if I move my head left to right there is movement in opposite direction on still objects.
Example if you pop up the simple vr menu put it in the middle, if you move right it will move to the left a little.
That is mostly what gives you motion sickness, witch I am still feeling right now.
Also the distortion is still there when you are just in the main menu looking for movies (simple vr) it goes away when you start a 360 movie.