Team leader treats me diffferently?

In the middle of June I was transferred to 'S' department. It is just a month ago. The male team leader is in his late 60s. Before I transferred I was in another department, this team leader at times will talk and joke with me. Until few months back when he heard am going to his department he stopped talking to me totally. First day when I report there he just seem like a stranger and distant to me. Even a stranger can be warm and friendly but not him. He even asked other colleague to pass message to me. I have been working 8 years in this company and has 4 team leaders who are work professionally and no problem at all. I have never even worked with him how could there be personal conflict? Working life becomes an emotional roller coaster. He is a re-contract retiree who choose to remain in workforce. I don't think am a threat to him as I am living and working as a low profile person. Your advice is very important to me. Thanks