You may check with a specialist but the same happened

to me at that time. He was too so absorbed in watching videos and I couldn't stop him. So I thought he might have autism since he knew the letters but didn't like to talk. Then I talked to my psychology professor. She told me not to worry at all because she met him before and she said he loved people. So there was no way for him to be autism. So ask yourself. Does your son enjoy seeing people around? Then he should be fine.
As mothers we worry too much. A friend who is a doctor told me she was worried since her baby didn't have hair when he was little. Then another old doctor told her,"Have you ever seen babies who are bald?" Today her son has very sick hair.