SanDiego1K:

Although my trip was already ticketed, it is not past the ticketing deadline. I don't know if this becomes moot once the ticket is issued. Also, my impression was that Europe was Zone 2 or 3 and not Zone 1. Even if it does require ticket re-issue, my earlier changes did not affect the fare and as the ticket has not been re-issued, I would think I am still okay.