Yeah that stood out for me too OK I m white but I have worked with Indians with the Forest Service for a long time and have heard both Indians and whites on rare occasion use rez as short form for reservation and it never raised an eyebrow It s just inoffensive casual slang as far as I know I ve never said rez myself because it would sound so presumptuous even though I am on reservations now and then I mean who am I kidding The rez But I doubt that it s a racist term if you are a non Indian