Welcome to the world of security paronia in the post Sept 11 travel world. Security guards are becoming more aggresive (good or bad I am not the one to decide but my feelings have been made crystal clear on previous threads), but the aggresion shown to you was uncalled for. The "random" search is supposed to be done as to inconvience you as little as possible. The search does not seem to be any different than any I have been subjected to, but the fact that you were singled out by the security guard and gate agent at boarding is unacceptable in my mind. I would write a letter to NW with copies to FAA and the security firm involved.