It's not normal, but certain people, some always, some just when they are under stress, simply do not feel pain in the same way as most humans do....I have a very high pain threshhold, since I suffer from severe chronic pain, so cutting into my skin or it being burnt I don't even notice ! My body alarm system for pain probably does not work properly anymore since it's been disabled by the pain that is constant (ot at least that's my interpretation, I would love to hear from someone medically expert about this !).