My Son is doing that right now, a lot of baby talk that I can't understand.
We just got him evaluated by a Speech Therapist. He is developmentally delayed, so we wanted to make sure he is on target by getting him tested. He didn't need the speech therapy, however his receptive listening skills are behind and she said to keep an eye on it.
I would keep an eye on it, I wouldn't take your child into the Dr. for this now. He may just be playing around with you also. If it increases or gets worse and uses less and less normal words and continues when he is 3 or 4, then I would seek help.