Obsessive–compulsive disorder

A person with obsessive compulsive disorder (OCD) is very prone to healthy habits, such as wash hands, but in a irrational frequence. A professor that shares my room is OCD. I seat next to the window but he has no windows. We know that closed windows are bad to health, mainly when someone has some virus or bacteria. Yesterday he was very bad, coughing a lot, but it was also very cold. 

We do not have conditioning air for warming the room. As I sit next to the window, I noticed that the air outside was hotter than inside. I told him that it would be a good idea to open the windows and doors to let a hotter air come in, but he refused.

Why?

Because nobody wants to be in a closed room with a sick guy. Thus, he thought I was just being selfish - opening the window for my sake, harming him with a cold air.  Anyway, I left the room because I had to teach.

Later, when I was leaving the job, he told me to close the windows. Amazingly all the windows were opened because he did it in my absence.

I was surprised to his change of mind. 

He told me that he was not trusting me, but when he walked outside, he noticed I was telling the truth. He concluded I was being selfishly generous.

I concluded that he was seeing himself in me that is,  he thought I was acting in a similar way he could do.

Isn't normal to look ourselves in others? Certainly we may misjudge others due to our dirty eyes.