Before Chris Thile became a reasonably big-time solo artist (and an NPR rock star) he was in a progressive bluegrass band called Nickel Creek, a trio of mind-blowingly talented youngsters whose playing was deeply rooted in bluegrass and old-time music but exploded the boundaries of those styles. Just listen to “Ode to a Butterfly” on this, their third album: it sounds like a traditional fiddle tune except for the crazy time signatures and the equally crazy arrangement. And the whole album is like that: brilliant, exploratory, maybe slightly baffling.