Adolesecent growling at my son when he enters my room
My first time posting here.
We have a eighteen month old male, Zeus, working line, unneutered. Everything has been going well with him so far. Friendly with people, reactive to dogs, but getting better. He was reactive to other animals(horses, goats, cows...) as well, but has improved a lot with counter conditioning.
Recently he has started growling(low growl) and trying ot block him at the door whenever my thirteen year old son enters a room I am in. Usually Zeus is like my shadow. Although he loves playing with the children, and follows them around the house or on offleash walks. They train him as well every once in a while.
I am a bit confounded with this new behavior. So far all I have done is 1) I just started putting him in his crate if I am not watching him or if he is in the room with me. (his crate is in my room, but he hasnt really needed to be crated till now)
2) having my son take him out of the crate and train him using treats.
3) having my son give him his food.
I also have two girls and Zeus is entirely fine with them when they come in to the room.
My son has always been kind, and gentle and I have made it a point that they are never unkind to the dog(leave him alone if he is tired and resting, dont tease him with food or toys, let him eat in peace, etc.)
I understand this is very serious and should be nipped right now.
Is there anything else I should be doing? Appreciate all advice.