Top of Hyatt Extras May 9, 2007 email, exactly as OP reported:
Welcome SanDiego1K GOLD PASSPORT # G000xxxxxx MEMBERSHIP: Diamond
Join Hyatt Gold Passport® and earn a free night after your second stay. Learn more about becoming a Hyatt Gold Passport® member.
Since I'm already a diamond, I wouldn't have thought that invitation to join was meant for me. After all, I can't join - I've already joined. Has anyone besides the OP and richee called for the promo, and had Hyatt refuse to honor it?