You have stumbled on one of the reasons many frequent cruisers (including me) try to never use cruise line arranged air. Personally, we prefer to always do our own air and fly-in to most ports one day early. Your 40 minutes meets the minumum connection time for most airlines at DFE (35 or 40 min) so there is not much you can do other than to call RCI and complain (perhapd they can still change your flights). IMHO, your major problem will be your checked luggage. If you are flying-in the day of your cruise, there is no margin for error with luggage (another reason to go at least one day early). So, pack accordingly and make sure you have essential clothes for a few days in your carry-on.