It was a rare moment of graciousness from a comedian whose standup is often skewed, fatalistic and filled with outlandish exaggerations. Like Letterman, Macdonald has "no truck" for the sentimental, either: His comedy has a bumbling, bone-dry cadence that lulls and misleads before turning into a sharply caustic punchline. Still, on the Season 3 premiere of his sporadic web series "Norm Macdonald Live" on July 25, MacDonald reunited with Letterman for an hourlong interview, and couldn't help but sound sentimental again. The wistful conversation touched on the state of late-night television and old mentors such as Johnny Carson. "Why don't you get one of those big 'Charlie Rose' desks and get back on the air?" Macdonald asked Letterman, who laughed but, of course, declined.