He knew when, because he'd felt the same thing eventually himself. "We're gonna have to leave them behind someday anyway, unless you really wanna stay there the rest of your life." Which he'd been tempted to do for a while. Things had been good. But there was so much more out there to discover, and the desire to settle somewhere for a while had passed. There were a couple people he could blame for that, but there wasn't much point - he wouldn't have been happy on Pandora forever anyway.