I saw another pic of the crack from far and i didn't think it was true but, heres the proof...looks like it runs all the way down to the pivot bearings
I wouldnt say thats a break, there's no paint chip and its a consistent width etc, doesnt look like a break of the metal imo. I'm no engineer though. Looks a lot like a sticker or a fluid run of some sort.
I'm confused by it too, I just can't tell if its a sticker or a crack, here's another pic though. To me it kinda looks like a sticker, but then it looks as though there's separation right under the clamp, could just be an illusion though. If it is a crack, it's a good one.