the elevator has been reshaped for high speed effectiveness. It's more bulbous. This is to get it out of the boundary layer of the horizontal stabilizer and would have been selected by his aero guys. There is a basis for this from the old NACA reports that I was going to dig through again, but if a shock did form, it will form on the deflected elevator itself and not on the hinge line or ahead.
Very interesting, thanks for that. Any idea why they felt the change necessary? Were they running into a (stick force) stability issue?