Hi! 
!! Question time !!
First, let me say that my Riley loves every human he meets... Lately though he has changed a bit. (past 3 or 4 months) He is fine when someone comes over. He wants to be petted, played with etc. until I come in the room... Therein lies the problem.
If I am near someone, (even if they have been getting kisses from him and playing with them) and they reach down to pet him some more, he growls and snaps at them! (he hasn't bit anyone yet, but definitely warns them pretty aggressively) Then, if I leave the room, he will go back to being lovable to them, and even sit in their lap if they let him. 
If he is on my lap, 
no one can touch me or even get too close for 
any reason. He barks loudly and growls. (except for little Izzy, his sissy. He lets her get between us
 
 
I correct that behavior when he does it and eventually, he becomes OK with the person being near me if they stay long enough, or comes over a few times.
Is he protecting me? Is it a normal behavior?