Just an FYI on this: I received this email as well, and it states in the fine print you must have the Penfed AMEX card, not any other Penfed card (I have the Visa). Here are the terms:
To participate, you must be a PenFed member and have a valid PenFed Premium Travel Rewards American Express® Card in good standing and be a legal U.S. resident 18 years of age or older.