I think I understand - when you look with one eye through the TRS-25 and the other eye is open looking at the same target through bare air, it looks to you as if the image of the target/surrounding area in the view of the TRS-25 is visually "shifted" one side or the other, so the two images don't line up in the brain, is that it? This might mean the glass on some nominally 1X optics might actually have a slight magnification effect, which might cause that odd visual effect.