It was actually covered a LOT in the media, and in Wizard Magazine, EW weekly, and such. But, if you truly noticed that on your own, then my GOD you don't miss a thing. I saw the movie like 5 times and never ONCE did I catch it. haha My friends thought it was the funniest thing EVER that I kept missing Cap's shield!
Kudos to you for your keen skills. Apparently, I miss all the little things! LOL
Its even cooler as an afterthought because if you follow Comic Continuity, Tony Stark actually gave Cap an Improved version of his shield that he used really briefly...one or two missions...then went back to his Operation: Rebirth version so the strange look of it fits right in with that.....