I flew yesterday WN out of MDW and used the First Class/Medallion lane (since I was flying in F***) and after you get your TSA check, about half way to xray, there's a guy asking to see your BP to verify your status for access to the priority line - (very nearly his words). I flashed my DL-DM card with my WN BP in hand - and he didn't even blink!

*** They say that EVERY seat is F on WN!