Apparently it was in connection with an airline promo. I wasn't given any details about what that would have entailed, but the CSR indicated it was a gold status offer that I would have had to activate within a short timeframe. I clearly didn't, since the card is 5 months old and I've not done a thing with it until today. The account is now active, just not as Gold VIP.

Let that be a lesson to me, I guess. I snooze, I lose out on free 20 months of Gold VIP status.