I agree w/ the others, you aren't causing any harm. If it's soemthing that bothers you than you could work on consciously catching yourself but I really don't see why you'd need to unless for you not others. I talk to myself when I'ma lone ALL THE TIME! If I'm not alone it's internal like crimgoddess said. For me I know I'm an analytical person and I think it's just part of it, I don't knwo if that is so for you too. But I think it'skinda cool.