I got the store to cancel my purchase and got it somewhere else. I got the 2012-edition this time, old style lens cap, which I love. And the mechanics feel MUCH better! No Noise, no squeaky AF and if anything this is even sharper at all focals.
I got an explanation from the rep guy as to what causes the noise (please note I'm simply quoting him as I have no idea about this myself)
He said there's a brass or copper band around the inner barrel that has a brush mounted to it that reports focal length to the camera. And he had taken in 5 (!!) 24-70 2013 editions with the same exact problem. And he said that brush is simply mounted to hard so that it grinds, it's nothing faulty, and it would loosen up and become normal. He understand fully that I didn't want to wait to "break it in" so I simply got my money back.
interesting. i'm glad it wasn't just me who felt it was worth returning it for though. I was starting to think it was just me being fussy. it must be quite a stiff brush attached to make such an audible 'tick' sound. it certainly didn't sound like it would go away any time soon to me.
as you say the ones made last year were fine. my new copy was made i believe in october of 2012 and is dead quiet and nice and smooth. also it appears to be as sharp as the returned copy. i need to go out and do some proper shooting though to confirm this.
EDIT: huh just seen your reply neuroanatomist. that's how i aged my lens too