Welcome to 9/11 anniversary travel week: American Airlines canceled a flight from Dallas-Fort Worth to Washington today after a passenger reported "suspicious behavior" to the crew before takeoff, reports NBC. Two men were removed from the plane for questioning, but they were soon released and allowed to book another flight. The plane had to go through another security sweep (nothing turned up), and the delay grew so long that American just canceled the flight altogether. No details on what the "suspicious behavior" was. (More American Airlines stories.)