“Travelers at Sea-Tac and dozens of other major airports across America are being scrutinized by teams of TSA behavior-detection officers specially trained to discern the subtlest suspicious behaviors.

TSA officials will not reveal specific behaviors identified by the program — called SPOT (Screening Passengers by Observation Technique) — that are considered indicators of possible terrorist intent.”
– source: seattlepi.com

No wonder which the manual book they used to develop this new kind of screening:

“It was terribly dangerous to let your thoughts wander when you were in any public place or within range of a telescreen. The smallest thing could give you away. A nervous tic, an unconscious look of anxiety, a habit of muttering to yourself — anything that carried with it the suggestion of abnormality, of having something to hide. In any case, to wear an improper expression on your face (to look incredulous when a victory was announced, for example) was itself a punishable offence. There was even a word for it in Newspeak: facecrime, it was called.”
– 1984 by George Orwell

What woud be interesting is to follow the propagation of airport security into real live. Today for example, it’s mandatory to put your name on your luggage when you travel by train (in France at least), is it something coming from airplane security?