Some dogs have more of a protective instinct than others. My Lab hardly ever barked, just looked at the door and maybe one woof on account of the Chi's barking. And one other time when something really weird happened (someone trying to jimmy the door) late at night and kids were home alone, she ran down the stairs from my then 13 yr. old son's room and was gnashing teeth and vicious at the door. That was the only time....otherwise, she never barked. Same with my GSD. Same thing happened in another house. Weird. My Doberman, on the other hand started getting a serious, throaty low growl and menacing, vicious sounding bark at around 4-1/2 months.
Is Kodiak something like a Rott/Shepherd mix? Or Shepherd/Lab? I would guess that he will get more protective in a few months time....maybe not till he's 2 or 3. They really do vary. But that's my guess....that he will develop that protective instinct and begin barking on his own in time, as he grows up. It's important to socialize him a lot now and always so he learns what normal is...normal, friendly strangers, so that if something abnormal comes along, he'll recognize it as that and react appropriately.