I really liked the thing when I saw it on Craig Ferguson. And then I saw it on Conan. And then it was in Rolling Stone. So... the only time he didn't wear it was the HBO special. And he was wearing a sweater, so it could've been there underneath.
And nobody really talks about the Ferguson performance. But I thought it was better than the Conan. Except I liked the thing about Light(Like?) of the of Conchords.
The HBO show was filmed quite a ways before the Conan and Ferguson spots. And iirc on the guys site, they say that the striped sweater is new, that Bret bought it about a month before.
Does that help?
And o dear, I do rememeber way to much trivial detail