Thanks for all the replies.
I now know less than when I started <G>.
To summarize, nothing that I know of changed. It was a Concur booking and has been for years for the same itinerary and I got precheck without fail. My profile had a valid TTN but it somehow was not attached to this booking. Per DL res future bookings have my TTN attached so it may be a one off problem.
I tend to blame Concur due to other glitches in past bookings, mainly Hampton reservations.
I just know that when I don't get precheck, I'm dumber and slower in the line than the average traveller!
Jim