A similar thing happened to me last November with a general strike in Greece. When AF got the official notification it was too late to do anything! The result was a day longer in SF (obviously on my expenses), a new ticket for reasons of incompetence of Delta agents (got reimbursed 3 months later) and lots of nerves broken (plus other non-vital but important body parts). It is amazing (though to some degree fully understandable) that airlines never react on unions' notifications but always wait till the last moment to get the word from civil aviation authorities. C'est la vie, unfortunately...