It is always okay to question authority. You are a human being, not a machine; do not let those above you trick you into thinking otherwise. Even the most trustworthy of people make poor decisions and it is your job to let them know when. If they tell you to jump of a cliff, do not do it. The most common situation when this comes into play is with the government. Tyrants come into power when their citizens are too scared to stand up to corrupt authority, with Nazi Germany being the prime example. In the aftermath of World War II, it was decided that the blame is equally shared by both those in power who give the order and those beneath who follow through with it. It takes a great deal of courage to stand up to the power that governs you. Sometimes it could cost you a fine, jail time, or even your life. Dr. Martin Luther King Jr. was jailed and eventually killed for his protests against the racist laws that ruled over the United States at the time but without his bravery and sacrifice, the injustice may have never ended.
Do not sleep while the higher caste lives. Make your decisions in life based on reason, logic, and morality. Anyone who defends their position by saying "that is just the way it is" or "that is how we have always done it" is not worth trusting your life to. Any leader who values their own wellbeing above that of those that they are in charge of has selfish, anterior motives. Reject these authority figures, they are not worth following.