Okay, so we all know that Butler had aged 15 years by the end of the Eternity Code, but had laser skin peels and whatnot to appear like his rightful age again, since he and Artemis needed to be mind-wiped. And then at the end of the Lost Colony, he naturally aged 3 years waiting for Artemis to come back. Throughout Eternity Code, Lost Colony, and maybe Time Paradox (?) we get some insight from Butler as he remarks how old he feels, but I think this was curiously absent from Atlantis Complex.
Now, a friend of mine thinks that Butler was properly de-aged (not just the outside but the inside as well), but I don't think I saw any evidence of that in the latest book. Did I miss something, or is it just wishful thinking on my friend's part? XD;