I've also been protected on US. This past Dec my flight from FCO was late arriving in PHL. I managed to get through customs and to my gate about 15 minutes before departure. I actually didn't know I was protected until after I was home I received a text, email, and automated phone call telling me my flight from PHL-DCA was delayed. I'm glad I made my original flight as it would have meant a 3-4 layover in PHL!