one more clue:
looking at the edit, i can see that one other change was made to the text: from "and there you appeared" to "and there you appeared again." which seems to me an odd change for someone else to do besides you.. maybe you edited that one line and somehow the quote got messed up..
regardless, while posts are each tagged with the ip of poster, mods aren't. though the log of user logins does list ips (and only shows yours), i am modifying the post modification log code to record ips as well, so that should solve the mystery if it ever happens again.