I noticed this when I first came across it in the game a couple of years ago, and it's bugged me ever since. Last week, I was in the instance that features it (the Antitower) and another player ranted about it too.
What's particularly annoying is that I don't know whether it's like this by accident or design. If it's there by accident, that's easy to explain but it needs fixing. If it's there by design, then either it's saying something about the game (it's just before the final boss and could be saying it's a bit off-kilter) or it's saying something not about the game (maybe the person who placed it incorporates one conscious flaw every time, as is traditional in Islamic art).
Whatever the reason it's there, though, I wish it weren't.