How often do casinos actually change their chips?

I'm going to Vegas in July and half some chips from the Wynn that I found left over in my suit case from my trip in September of 09. I would assume that I can still use them.

Are they burgundy $25,000 chips? If not, and they are red,green, and black they are probably still using that same batch. I know they wash the chips but that don't mean they will eyeball you.

Before you go to the cage,take a quick look around the BJ tables etc.and see it they are the exact same colors etc as the ones you are holding.If they are an older issue,they are worth more than the current chips in circulation to collectors.This applies to all casinos,but at this time I think the Wynn has had no new releases,but come July that could change.