One way or another, we're gonna have to hunt it down, unless it decides to show itself on it's own. We're gonna have to beat it, too. [At least, that's what's happened last time Bowser was kidnapped and sent to another dimension. Really, every time Bowser goes somewhere it ends with a final boss fight. Though as certain as he is that a final battle is coming, he's just as certain he'll win.]

But before then, yeah, we need more evidence.