I flew on UA from DCA to ORD on Jan. 18. All checked luggage had to go through an x-ray machine and UA was still in a learning curve but the lines were very short but a little confusing.
My connection from ORD-TPA we had to pull back to the gate, as there was some confusion about a voluntary bumped passenger who stayed behind but whose bag was still on the flight. After a 10 min. delay they decided that it was OK to leave the bag on board.
My return TPA-ORD and ORD-DCA on Jan. 21 was uneventful with no additional delays or security procedures in evidence.
Warning: Those X-ray machines will destroy any photo film according to the tiny sign on the machine.