Was it mean of me to laugh looking at him like that?

I have shared here before that I have been going to an institute to learn the programming language Java. There a guy has been coming in our java class for the 2-3 days. He is from Bhubaneswar in Odisha, India and I am from Siliguri and Falakata in West Bengal and now we are both living in the city Bangalore in India. Odia and Bengali people are similar so we tend to get along well. We are both in last year of college and about to graduate soon so he is either 21 or 22 now and I am also 22 now but he is quite overweight and he looks younger than his age due to lack of facial hair. Even I look younger too as i don't keep beard but i have some upper lip hair whereas he doesn't even have that so Idk i end up laughing looking at him. He was sitting behind me in the class today and I was looking behind at him and laughing. He was confused at first why I was laughing at him for no reason but later he was also smiling back. Do you feel it was mean of me?