There was a moment near the end of Monday's "Austin City Limits" taping at ACL Live when Willie Nelson seemed to pause for a moment and take it all in. He'd just finished "On the Road Again," but before he followed with "Always on My Mind," he gazed lovingly upon the crowd, which roared with appreciation. We all knew what we were witnessing. He did, too. Judging solely from the set list and the personnel, you might have thought this was just another night with Willie — and in some ways, it was...