One hour isn't a lot unless you arrive off a connecting flight. I'm sure if the airline had brought any of my previous flights forward by an hour I would have still been on time to make all of them.
You could of course just ignore the message and turn up at the airport as usual. If you miss it then it'll be up to the airline to get you home.

Wouldn't have thought it was a good idea to be timing dives to within one hour of departure time anyway?