I had this problem a couple of years ago, when I failed to notice that my license had expired a couple of days before a flight. I was sent from the elite security line entrance back to the ticket counter, where I received a new BP with SSSS on it. That signaled the security agents to do a more thorough screening --- body pat down, open luggage, etc. Nobody was nasty about it; that was just the procedure for that situation. On my return flight I allowed extra time for the extra screening. It sounds like the regulations may have eased up recently.
The more serious consequence of my lapsed license was that I had to cancel a rental car reservation.