There was a disconnect between the designer and the developer. The designer created the comp in Photoshop with the text exactly as they wanted it to appear. A developer had then taken these specs and made it look like the comp during development, but something was lost in the translation. CSS does not have the fine control of text that Photoshop does, and each browser displays text a little bit differently.
This is where the Web Font Viewer comes in.
Another tool to help designers and developers see type in real web context, and talk about web typesetting without getting wrapped up in layout. I bet this is super useful for teams and clients.