J.H.
Just remember that he is learning and growing and this is a part of that and nothing more. I would bet you a dime to a donut as the old schoolers say, that this happens with many children his age. It is the same with my grandson and was the same with my own son, (now deceased. I would be concerned and attentive to any inappropriate behavior and address it calmly, but immediate giving the child an explanation as to why this is not good to imitate. He is finding himself and finding his way. This is common with siblings too. Being that he has no siblings like my grandson, and my son at that time in his young life, as my son grew and got older, this disappated. I am sure you will find it to be the same with your child too. Relax and let him explore. If he presents extreme or inappropriate behavior, and sometimes he might, be diligient to address it, otherwise let him be if he is not hurting anyone, himself or anything. He'll be just fine with your love, guidance and positive active parenting as you are showing you are doing right now with this question.
Good luck to you!
Jen