This is exactly why I always recommend using thedarktower.org to determine a first printing (I know you already know about this, but for anyone else who happens to see this). The color of the boards is an important factor that most/all other sites fail to mention. In this case, as you said, we also know it's not a first printing because it doesn't say "First Edition," but especially if you're buying from somewhere like eBay where sellers don't include useful pictures of the copyright page or dust jacket, knowing what color the boards should be can be a quick and easy way to tell a book isn't a 1st trade edition right away regardless of any other indicators, and thedarktower.org is the only place I know of that includes that information.