alph2z
Ttcse's comment is correct. Aft swept wing aircraft begin to stall at the wing tip and the stall progresses forward and inward toward the fuselage. The aerodynamics guys can twist the wing and play games with the leading edges to modify this somewhat but at high enough angle of attack it will happen.
This tip stall causes a nose up pitch moment as the lift contribution from the ends of the swept wing decreases.
I've had a lot of practice over-rotating off cat shots and I can tell you from personal experience that it used to take up to full nose down stabilator to get the nose moving back down where it belonged.
