Ok, so the experts have solved the puzzle now.
Somatogravic illusion is the culprit, case closed...
It does frustrate me - just because it hasn't happened to you (yet) doesn't mean it never will, or won't happen to someone else. Evolution is something that takes thousands of years - or are you somehow different?
What frustrates you? That I have never experienced SI....?
If I did, perhaps I should hang it up.