Hi, I'd like to help you with your question.
This can be a normal reaction for your child. Everyone reacts differently to stimulation and excitement and this could be his way of expressing himself.
If your son has had no other symptoms, particularly neurological, then I would not be concerned, especially if he is communicating with you during this time and seems aware of his surroundings. Mention this reaction to his pediatrician next time he has an appointment just as a precaution.
If, however, you feel there are other symptoms you are seeing or are concerned about, make an appointment to see his doctor as soon as you can, just to rule out any other physical problems.
I hope this has helped,Kate