I read your same question at another website.
TBH what do you expect a dealer to do about this now
The warranty is long since expired and as long as you have, though still shouldn't need it, the original sales receipt, it's all pretty academic now. Even if the supplying dealer wanted to start over with a correctly dated warranty card, they can't as they don't have a pile of plastic cards to casually re-issue one retrospectively.
It does seem like it may have perhaps been presold but may never have left the shop. Perhaps the original intended buyer couldn't complete on the sale, credit card refused ??? but by then the warranty card had been completed. So while the dealer was perhaps wrong in holding back on telling you, to discover it sooooo long after you bought it means you can do nothng about it as far as i can see.
Question, does it really matter