Answer: Changes to the GlobalFlyer fuel systems
last flight that prevented the loss of fuel this time?
There were no changes made to the plane from the last flight which flew out of England last month. There had been changes made to the plane before it made the flight out of England.
Mission Control theorizes that one of the reasons that the fuel did not vent over this takeoff may have been because Steve climbed slower and pressure inside the tanks had time to equalize to the pressure outside.