Just out of curiosity, what band was it? I lurve Celtic music.

It was Bohola. Three man band based out of Chicago.
http://bohola.com/
Below's the blurb from their site, and when they say the accordion guy is a virtuoso, man do they mean it. It was worth it just to see this guy play.

Irish music’s accordion virtuoso Jimmy Keane along with fiddler extraordinaire Sean Cleland and the remarkable dordan player and singer Pat Broaders comprise bohola, Irish music’s newest “supergroup” as penned by The Irish Herald. bohola play a driving, muscular and yet very emotive style of Irish music with deep roots in the ‘pure drop’ tradition, which has been forged with the raw and gritty urbanized musical vernacular of the Irish-American experience.