I don't find it abnormal at all. You are reading too much into it. Every dog is different. Just like people. My Trixie only barks when she is playing and being wild. And that is only like 1 bark. Don't look for things that are wrong. Just enjoy your little guy. Believe me if something goes wrong you well know it. Like the saying goes,"if it ain't broke..don't fix it" That's just your little guys personality that's all. leave him be!!
