I always thought that the line "Whatever you say, I won't age a day... was a hint to another character in the game. I asked your opinion time and time again, and no one answered me.
However, I have looked at a site that transaltes the Japanese version, to English - they never use that line in the Japanese version - so unless Woosley was clever enough to think of a piece of foreshadowing all on his own, that is just a random lyric to a song, with no meaning to the storyline. Shame really.