Question asked: Are language problems something to be concerned about?

My 9 year old son does fairly well in school and is very good at maths, science, logical and non-verbal reasoning etc. He is also quite sociable and makes friends easily. However, his vocabulary in both English and Malayalam are very limited despite being exposed to a lot of books (he reads a lot but prefers comics and graphic novels). Often I think that he reads on without understanding the meaning. He has trouble expressing himself and cannot often report events, conversations etc. clearly. He also can't stay still for long and is quite fidgety. Is this something I should be concerned about or is it simply normal?