Is being socially reclusive okay for a graduate student? I am Ph.D student in computer science and mathematics. I have published a few research papers and working on some papers. I am an after mid-stage student and I spend almost 90 percent of my time in my study place. I do exercise for half an hour per day. Before joining the Ph.D I was shy and now I am not shy, but my collegues around me now find me a strange person. This  is due to the following reasons:


Many times I don't talk to the people whom I meet while going back to my room or some other place. This is because I am in a thinking mode, thinking about a research problem.
I don't participate in group activities as the feedback given by my collegues. 
I don't congratulate (much) or wish people around me like on occasion like new year, birthday etc., but I congratulate people around me on their research or academic achievements. Let me elaborate more, I do congratulate my friends and family outside academia.


Although I know my behavior, when working I try to avoid distractions. Many people find my avoidance weird. I can't be perfect as I spend most of the time on research problems. How to tell them I am not avoiding them?

Note that I have many friends, but not like hundreds, but some. I usually talk with them every day. 

Question: Is being weird okay for a graduate student?
Is "OK" good enough?

It's "OK" to be strange and reclusive, but being socially reclusive will stunt your career long term. You will not be considered for projects, not be sought after for collaborations, students who go on to success will not be as likely to reference your papers or publications in informal situations, and you will be less likely to be considered for promotions/tenure/etc. Not maliciously perhaps, but the social recluse just doesn't come to mind as often as more gregarious colleagues do. It essentially closes doors unnecessarily. This isn't to say that you shouldn't be true to your personality, but the fact is that success in any field of endeavor, even academic ones, is as much affected by your social skills as your intellectual skills. 

Look at the mid-nineteenth century physician Dr. Ignaz Semmelweis, who identified that hand-washing and sterilization of instruments drastically reduced incidence of death from childbed fever. Because of his poor social skills (note that he was actively abrasive and confrontational rather than merely reclusive), he was unable to gain acceptance for his findings, and unsanitary medical practices continued despite his efforts.