After listening to the complete score from Episode III, I noticed a theme played when Darth Sidious instructs the recently knighted Anakin of his mission on the Jedi Temple. It's from "Shadows of the Empire", featured in "Imperial City" (the choral announcement before the march). I'm not sure if the theme was already used in Return of the Jedi, but I doubt it, since I haven't found any info on McNeely's soundtrack (including filmtracks). If indeed the theme was by Joel, what an honor for him, don't you think?