Butcher is a master of the long game.

In Dead Beat (book 7), Dresden is being attacked by a former Denarian, and is in dire straits, and is lamenting "Where's Michael, where's the Knights of the Cross?" Who should show up to save his ass? >!Butters!< We don't think much of this at the time, as that's a character who was already involved in this situation.

But then, in Skin Game (book 15), >!Butters takes up one of the Swords and becomes a Knight of the Cross!<.

It's not as long of a gap as yours, but it's considerable foreshadowing of a major event, and not just a throwaway line into associated gag.