I agree. IMO, the stroke has changed his facial expression.
I understand that he had the stroke a while ago - it definitely affected one of his hands which is always clenched into a fist. It may have also affected his walking. But he seems so somber - always under a black cloud. Even with his kids, he never seems happy or smiling. It must have been very hard to live with him. I know that strokes can change a person's personality.