So others have been there, eh?
So we know Hitomi's grandmother was there, but that was way too early for her to bring a CD with her. That means there has been at least one other recent visitor to Gaia, or someone from Gaia visited Earth and brought that back with them.
I'd be interested in a spinoff series that takes place before or after the regular series. One that's not about the characters from the original series (though I wouldn't be opposed to them making cameos) that takes place in Gaia. Thoughts?