Dissociation has a million different levels to it, but in the most general sense it means separating emotions, facts and reality.
It sounds like dissociation, and everyone has experienced it before. Since you said it doesn't cause a problem and happens rarely it may not be enough to be called a disorder, but a dr would have to tell you that.
It sounds to me like you learned a coping skill during your truama and have found a way to use it to get through overwhelming situations. I sometimes enjoy being able to separate myself from stressful stuff around me when I get upset, but sometimes it gets in the way and causes issues. It all depends on how it affects you in those situations. Dissociating can leave a person vulnerable if they don't have control over it or it is extreme.