It just happens. After he becomes mad, he doesn't blink his eyes. I didn't notice it when I shot the film. Only when someone asked me whether we did it purposely, did I notice it. In the climax scene of Kireedam, you see him clenching and unclenching his jaws.
People do that when they're tense.
All this comes to Lal so naturally. Recently, Madhavikkutty said that Lal was born in the wrong place. His potential is so much that I don't think an Indian director can ever make use of it totally. He is a superstar. People adore him.