But it was a false alarm! According to Reuters, a crew on a United flight from Los Angeles to JFK Airport (with Cairo as the final destination) was suspicious of two Middle Eastern men because "one of the men got up to use the plane's restroom just before take-off, ignoring orders from the flight crew to remain in his seat."
Some more details: A passenger said that "A fellow passenger jumped out of his seat, said he had to go to the bathroom, and then went inside the lavatory, even though the flight attendant told him that everyone needed to remain in their seats for takeoff. About 30 seconds later, the man returned to his seat without closing the bathroom door." Authorities removed them from the flight, questioned them (they were cooperative) and then decided they weren't threats. Still, passengers and their luggage had to be screened again while the two men were allowed to get another flight. Lesson: Obey the flight crew!
For a little levity, here's part of Harold & Kumar Escape From Guantanamo Bay: