Xeni has the story at Boing Boing. I guess despite their best efforts to find a comfortable accord with the label, the shenanigans that prevented them from spreading their latest viral video as far as they would have liked bothered them as much as it did fans and observers. They claim the split was amicable, which it may very well have been, but it is hard to imagine the experience as not being intellectually and creatively frustrating.
I think the band is extremely innovative, their latest video is proof enough of that. I am willing to take them at their word when they first felt that working with a label let them do what they love best and they now cite the same reasoning for striking out on their own. They certainly seem like the types to be open to experimentation and the possibility of failing instructively.
The most important thing is that they are able to keep creating in their own, clearly unique and enjoyable fashion.