The body language (mostly the way he looks away) shows he's lying about everything. Liars always look away and avoid eye contact.
He seems a little Asperger-ish to me. He and Dave both seem incapable of any real human interaction, now that I think about it. Loved Letterman when I was a kid, but I don't understand how anyone could have any passionate feelings about a late night host these days. So passé.
Professional liars body language is very hard to impossible to read. Actors, politicians etc. Leno has done years of lying sitting in the host chair. Don't believe a word that comes out of their mouths, unless there are some independent facts to back them up.