It never hurts to have an evaluation done. It's possible it is autism. My son didn't stop flapping until he was a teen. He is high functioning, and always flapped with excitement. This is something that normally babies do and grow out of quickly.
An evaluation can be done by a pediatric neurologist. Possibly a clinical psychologist that deals with children. If there are any developmental delays, you can go through the county health department, though the process is a long one.
Hope this helps