A face mask? Due to concerns about bio- or chem-warfare?

I remember back in... mmm, 2000 I guess, I flew out to California for a week. Going through the security checkpoint, both my father and I had leatherman tools in our pockets. The basket-poker looked like he was going to make an issue but the supervisor of the station said that they were okay. Then we spent five minutes trying to find out what other metal I had on me because the detector kept calling me a liar. Turns out it didn't like the steel zipper on my vest. <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />