This conversation reminded me of a wierd experience, sort of a reverse pothole. On a bright sunny day, I rode up a little driveway, planning to get onto the sidewalk. Except there was curb between the driveway and sidewalk which I could not see, due to the angle of the sun, the brightness, something. At the last second I saw it, and reflexively did what hipmama mentioned above, a lift/jump move. Scared the bejeebers out of me for a moment.