So sorry 13years, know that when you were hired if you put you could work anytime they keep those and anytime new management comes in you should always expect changes. But you have 13years experience working that great for the resume. Some time our pride gets in the way of logic, it's seem that you could have change yours schedule but you felt way should you. If I read this wrong i am sorry.

That's not really being fired for no reason. A management change can mean things are done differently. If the GM wanted to change your schedule, you should have said "sure thing" unless you had some reason why you couldn't (like school or child care). The fact that he's only been there 6 months versus your 13 years means nothing. He's the boss.

On the other hand, you should still be eligible for unemployment. That isn't exactly "cause".