There were several moments where Mordin actually experienced joy from those moments. One time he was performing Gilbert and Sullivan in front of an audience. The other time was when he was working with several brilliant minds about the genophage. The other time was when he had performed in front of the crew after they had survived from the mission. His favorite moment was when Shepard and he had spent most of the day talking about their homes and spends the rest of the time talking about anything and everything. It was a peaceful, relaxing moment he never experience before.