That's a good summary of the feedback effect taking place in MBS hedging. I think 3.69% was the high tick for bonds, though, looks like we are aiming for 4.60% real soon now, so that hasn't come to pass. The outstanding MBS universe has largely been 'recouponned' (i.e. most stuff has been refinanced already) so yields ticking up should make MBS a more stable and less gamma-y asset class.