This was in the NJ Star Ledger, and could be local. "American Express is now proudly accepted at All Sam's Club locations. And to celebrate, Card Members can get $25 back by enrolling an eligible American Express Card and purchasing a new Sam's Club membership at Sam's Club membership at Sam's Club by October 31st. Sam's Club memberships start at $45. (Enrollment is limited. Prepaid and Corporate Cards and Amex Cards issued by other financial institutions are not eligible. $25 back is received as a statement credit. Other terms apply.)"

I think because Costco is no longer accepting American Express. BJ's is still accepting American Express.