I don't know if anyone else is experiencing this, but certain gift cards are on sale in my Membership Rewards account.
For example, Neiman Marcus and Saks Fifth Avenue gift cards only cost me 8k points per $100 (redemption rate of 0.0125).
Oddly enough, when I checked my mother's AMEX account, they aren't on sale in her account and instead are at the normal rate of 10k points per $100 (redemption rate of 0.010).