Shy?

So far, so good with Collin and Stranger Anxiety. He will let anyone hold him that wants too and will not want to go immediately back to mom, dad or the person holding him before. However, I think he is shy around strangers starting about a week ago. If I (or another family member) is holding him and someone else walks up to talk to him, he puts his head down on the shoulder of the person holding him while still looking at the person that just walked up to talk to him. At first, I thought he was getting tired or was still tired if he had just woken up from a nap, so he was putting his head on my shoulder. Then, I noticed he did do this when a male would walk up to us and start talking. Yesterday, Chris had Collin at the bike shop and was introducing him to a male customer and he did it then too. Collin was not sleepy so I assume it's because he did not know the person. I thought I was onto something about him being shy around males but he broke that when he did it yesterday in front of a female at the other bike shop. He did quickly warm up to her and even let her hold him for awhile before he came back to me. We are going to a friend's house tonight for dinner and so Collin can play with their 6-month old daughter, Amelia.