No, he's not flying commercial in response to the criticism of his use of military aircraft for his "date night" in New York City last Saturday.
But he's using Dulles because it's got longer runways than does Andrews AFB. The crew of Air Force One needs the longer runway because it'll be topping off the 747 fuel tanks to the brim for the long flight from Washington, D.C. to Riyadh, Saudi Arabia.
It's 6,760 miles as the crow flies, and longer still in the curved flight route taken by aircraft. The 747 that serves as Air Force One has a range of 7,800 miles without refueling.
With its fuel tanks topped off, Air Force One needs at least 10,800 feet of runway for its takeoff. The longest runway at Andrews AFB is only 9,755 feet.
So the blue, white and silver 747 will be leaving from Dulles, where the longest runway is 11,500 feet, more than the required minimum.
It means Air Force One had to make a quick hop from Andrews, 10 miles to the southeast of D.C., to Dulles, 25 miles to the west.
It's not unprecedented for Air Force One to depart from Dulles, but it is unusual.