Here is the web site for Certainteed (you can see a picture of your selected shingle): http://www.certainteed.com/croof/crct00001p.html
I have the Certainteed Carriage House Shangle on my home and they are absolutely, positively flat. They are 1 year old and lived through a midwestern winter/summer with no change. Of course, my "Shangle" is fibreglass, whereas your shingle may be a different material. But I'd be suspicious of the installation, too. Get it checked by a Certainteed rep... it will cost you nothing and ease your concerns.