No, I wouldn't call it that. It depends on your definition of 'unhealthy.' If you mean does it damage anything, then no. It's very normal to do, and defiantly wouldn't have a negative affect on your physical, mental, psychological, it emotional state of being. If you mean does it make you different from other people, then defiantly not. Pretty much everyone does it. It's just a human thing. Talking to ourselves is just a thing that we do as humans. I don't know why we do this, so I won't say anything, but let me remind you that the human brain is the most complicated thing scientists have ever discovered in the whole universe, so who knows?
I know I know I'm telling them. It's completely normal. There you happy? Yes I am. Well good. What's that supposed to mean? You just never listen to what I have to say anymore. What do you mean?! Of course I do. No you don't. You never let me have a say in anything. I'm sorry will you forgive me? Yes I forgive you.
I think we do it to know if we are sane ,but were all askies so were all a bit nuts(: no but on a serious note everyone thinks about what they are doing and what is going on around them for example you asked this question that just means you are a active thinker some people are just more verbal than others nothing wrong with that its all part of being human.