I think this might be part of the TSA's new "visual profiling" deal ... where they look for nervious behavior etc. (there have been a number of news articles about this recently). Usually there is the "ID checker" and then off to the side is the "observer".
This probably belongs into the TS/S forum, but the new screening is just one big job machine... employ 2-3 people for maximum wage more instead of one minimum wage. The questions they ask are simply silly... ('so where are we going today', for example)