Not unusual for only one foot to turn out and could just be his structure. Does not mean anything is wrong with his elbows. It could affect his front movement though. As he matures and his chest drops and fills out it could turn the foot back in more.

I have a 8 month old girl who I noticed had one foot turning out at 8 weeks. I'm not concerned at this point in time. I had a male who was easty/westy and at two years old finally came together.