It doesn’t matter if you’ve just spent 30 minutes in the regular TSA queues, less than 5 minutes in the TSA Pre-Check line or 1 minute in the CLEAR area, all lines eventually lead to, not Rome, but the X-ray machines.
Once you’re there, it doesn’t matter if you’ve done this a bajillion times before, or even if you haven’t and know what to do to get you through X-ray quickly, you might go through the machine and get the random beeping alarm. Or maybe you got the dreaded SSSS on your boarding pass.
Either way, the TSA workers pull you aside and say you have to go through a secondary screening. It usually just involves them swabbing your hands (and/or your cell phone, laptop, food, bag, shoes, etc.), putting the swab in an Explosives Trace Detector (ETD) and, when given the all-clear, you’re told you can be on your merry way.
But why are they doing that? And why YOU?