Dulles has a lot of government contractors and big companies in the area, but that's about it.
What would be suspicious is if it went from Dulles to Langley, from Langley to Ft. Meade, from Ft. Meade to Quantico, and from Quantico to Alexandria....but Dulles to Alexandria is really standard.
edit: It isn't like it got back on a plane and went back to Seattle to be delivered to this girl. It looks like they straight delivered it to the wrong city. The government has pretty good OpSec when it comes to things like this. You think they would straight up route her package through Ft. Meade if they were planning to install malware on her computer?