My dog and testosterone

My male dog (neutered) gets really wound up when a teen-aged boy comes over... He goes into hyper play-with-me mode, play bowing and trying to get their attention. If they don't respond, he barks at them! I usually put him outside or on a down-stay when I think it will happen or it does happen. My oldest is 12, and Shadow has been reacting to him differently as well. I am not at all worried about safety, just wondering if dogs react to the hormones or if this is just my dog!