IIRC, the passenger list was sent to U.S. intel and they approved the take-off. Must have figured it out mid-air. Rut-roh! BO has a major “screw up” to answer for, again.
http://www.latimes.com/news/nation-and-world/la-naw-airline-terror7-2010jan07,0,2084702.story
Mid-flight - indeed that’s what the linked article states, but decide to wait til flight lands for questioning? - NO apparent notice to pilot ?