Yes. Ditto. An example, Continental Grand Prix 4000 s2 are hands down the most popular tire amongst locals and the price for brand new ones fluctuate from 900-1600NT. Which is quite ridiculous because as the consumer, you're buying new tires, how can price be that different. These are all straight from stores, not people who bought in bulk and re-selling.
For the conti grand prix, there's a theory that a serial number on the packaging indicates the year the tires were manufactured. However, no one has gotten around to prove this.
@Liuboy will knows tires, so you can trust his judgment, but my rule of thumb is, if you've gotten 2 flats in 1 ride, you swap the tires out. It sucks that you waste the inner tubes, but they're cheaper than buying a new tire when you're not even sure if the tire needs to be changed or not.
I actually have multiple slits in my rear tires and some showing beads, no flats yet, so I'm still riding them.