Two weeks after my initial post, I've received a Gold card valid until March 2015 -- giving me an additional year in which I'll get breakfast at Hilton and HGI properties, making them additional options for burning the points.

It would appear that -- because it was irrelevant to me as a Diamond -- I failed to properly research the validity of Gold status gained through holding a credit card, in this case Gold from a Citi Reserve card that I cancelled last year. With the expiry of my Diamond status next month, that will kick in.