Yes, it is common because of the psychological defense mechanisms of denial, suppression, and repression. These defenses are not problematic if they keep unpleasant issues from us when we are not ready for the full brunt of those issues. The defenses can get in the way of emotional healing when they prevent us from seeing the truth: I have been treated unfairly and I am angry about this. So, in the short run, the psychological defenses can protect us from being overwhelmed. In the long-run, slowly becoming aware of the depth of anger is a first step to healing from the effects of serious injustices.