Dav,
I honestly don't know. However, my best guess (but warning - this IS a guess) is that the aircraft flight controls are designed to get the aircraft to the optimum pitch angle as soon as possible after launch for the 'fly away' - this is a fairly low speed launch, I'd guess (again) at relatively low weight, so the exit speed will be low, giving a low pitch rate at exit.
My guess, therefore, is that what you have noted is the flight control system 'capturing' the aircraft pitch angle - as I understand it, the pilot has no direct control over pitch angle in the powered lift mode - this is all controlled by the computers. However, the pitch angle would be driven by the desired flight path commanded by the pilot.
At no time will I presume to know more than a hundredth of what John Farley knows, though.
Best Regards to all,
Engines
Last edited by Engines; 23rd Jun 2015 at 16:17.
Reason: Edit