Felix knew that he was here today only because Tsuru helped him survive, so he became rather emotional as he remembered her, unlike the other times when he didn't feel much.
His newly unlocked emotions completed him before he was an emotionless being. And that bothered him quite a bit because he didn't know why.
Now that his emotions were back and he considered Tsuru's actions, he realized why he had always been bothered. It was because he didn't feel grateful for what she did for him.
She took care of him the best she could as an old citizen who loved cats. When he was just a normal cat, and even though she didn't come with food every time because it was impossible due to her physical condition, she still came by to feed him when the weather let her, normally never missing a day.
