Yes, either you gave them the wrong information or they sent you the wrong drive. Maxtor made a mistake, it's not their normal policy. I'm sure they'd be glad to replace it.
However, you may have orginally sent them a 5400, thinking it was 7200 (like you bought it from a website claiming it was 7200, but they actually shipped a 5400 without you knowing). In this case, I don't think they are obligated to give you a 7200.