On our recent trip, we flew through our normal airport (Dulles) and I was surprised that they were splitting the incoming passengers into 2 different areas. 1 area was the normal body scan, shoes off, liquids out, etc. The other area was shoes on, liquids in bag, random chemical testing of hands (I got picked, they just swiped my hands with a cloth and put it into the testing machine). A metal detector was used instead of the body scan. This area was also separate from the TSA precheck area.
Has anyone else seen this at other airports? Is this a sign of times to come?