Hi,
How are you?
Yes most likely it stress is causing these symptoms. This could be a tic which may go away on its own.
I would suggest you to ask him to relax and take it easy for the next few days. Breathing exercises and meditation will also help him.
If the symptoms persist please convince him to see a doctor. Take care!
If this is an involuntary movement, it may be a tic.
Supplemental magnesium can help this. You can google for many articles.
Carol