I used to do this. I do agree with farmergirl that it is a bad habit and the good thing about bad habits is you CAN break them and overcome them. It may take some time, but you can do it. Ask yourself if this is something you really need to say you're sorry for and probably most of the time the answer will be no and you can stop yourself and eventually you won't be doing it so much.

Part of what helped me break it is my therapist telling me to stop it and then I got worried I was irritating him so I learned to stop. I don't think it actually did irritate him, but I felt like it did.