Never seen that before. Although maybe it's because I never played Dungeon Keeper. Another song as a reward, once again enough to make it all worthwhile. If I had to complain about anything at all, it'd be the same thing as any other Nerdook game: the music will make you insane after about half an hour of hearing it.
But it's not enough to stop me watching the frontpage for those signature guys with funny heads. Keep on keeping on.