Charles has correctly recited the written rules, but as your image satisfies all of them, I suppose that isn't particularly helpful. And especially for a person approaching 1800 RP images.
I don't happen to see much in the way of pixellation in the sky, but it wouldn't hurt to a) sharpen more (not mentioned by the screener but I think it needs it), b) gaussian blur the sky a bit, and c) when you reupload, it is always a good thing to tell the screener what has changed.