puzzling comment on CC statement

Our CC gives a 5% cash reward for gas, deducted automatically every month.

It is correct by my calculations, has always been.

Long ago I learned that a gas station can misclassify the gas transaction on purpose, i.e. instead of gasoline, they say it's for convenience store items, so the gas reward is missed. But this was 15+ years ago, never happened on this card.

Here's what the statement read: "We erroneously posted a credit to your account under "Nationals 10% Discount". We reversed this credit to correct this and it is reflected on this statement. We apologize for the error."

I wonder if "Nationals" is the baseball team, as the CU is in DC? I don't see any reversal.