Fantastic Batman Secrets That You May Not Be Aware of

On the wall are childish pictures of the Joker, one of which shows him coming out of his grave [Harley Quinn’s Revenge DLC]

Batman Arkham City DLC Harley Quinn’s revenge was an OK add on the story, mainly because it featured Harley who wanted to kill Batman, but it offered no real substance to the epic ending of the game. However if you managed to play the DLC, you will notice that Harley acquired pictures of Joker acting all childish which is nothing new, but something stood out in one of the pictures and that is, Joker coming out of his grave. Is this some sort of foreshadowing?