Another search shows the runway at Arnold Palmer Regional Airport in Latrobe, Pennsylvania, to 8,222 feet long. This is considered a little short for a fully loaded 747.
Andrews Airforce base to KLBE is around 170 miles. Thats a 35-40 minute flight. There is no reason to take off at Max takeoff weight or carry an excessive amount of fuel for such a short trip. If they are using the 757 (C-32) It is more than likely the Runway or the ramp was weight limited.
I am sure many of you have looked up Princess Julianna airport SXM/ TNCM in St Martin or maybe Maho beach on Youtube?
That runway is only 7,500ft long and KLM, British Airways, Air France, Virgin and many more flew 747s out of there loaded to the gills with passengers to Europe all the time, I think I read at one time, on the high end of the charts they were taking off at something like 80-84% max weight, hot, and humid.
I think the 747 is still the fastest of the Commercial Passenger Airplanes - but alas as all good things must - her time is coming to an end.