Did you know the game ticket was the same date as your already planned weekend anniversary getaway? If so, you shoulda said no thanks. If you figured it out after you took the ticket but before you told your wife, you should got rid of the ticket without telling her and having her make the choice. (Lame-o). Obviously since she reminded you of your previously scheduled plans, the commitment meant something to her. You shoulda said "oops", got rid of the ticket and then tell her, "I got rid of the ticket. Plan away".
Proper etiquette dictates that you don't commit to one thing and then accept another invitation.
The best bet for the rest your lives is to consider your anniversary a permanent previous commitment and don't consider other plans without running them by each other first.
Personally, I'd tell hubby to go to the game and I'd schedule our weekend getaway for another weekend. I don't really care for the way this guy handled it though. Presentation is everything:)