While Costco DID change their return policy, those items bought before the policy change are grandfathered in to the old rules.
At least from my experience.
I have 2 at home, and one at the shop. No problems (knock on wood).
Quick update...Found out it would cost 500+dollars to fix my TV 'out of warranty'. So we ended up buying a new Panasonic 46" Plasma at Costco for under 1000.00$. Got great reviews, so hopefully it lasts longer than the Vizio.