you cant make a call on the 1 sec difference.....MS is now on his 40-ish lap...which means that IF that car was filled to the brim it has to be quite a bit lighter than it was 40 laps ago..the start of the races sim...and he is still running very consistent 1.29s ish times. Id say they have to be toying around with engine maps to slow the car down as the fuel goes down..otherwise ANYONE in the pitlane could go determine how much speed they gained over the stint...IMHO

EDIT. 45 laps as of now..still 1.29 ish