It happens sometimes that you add someone or you are added by someone and you think that now that this person sees your profile, posting will never be the same. It can be a person that you admire or someone with whom you had a fight or a person that you have a crush on or your family member. In any case it is a person whose opinion matters to you or bothers you a lot. Now every time you post you are more self-conscious about that person than all the other followers. After some time the person usually blends with other people and the fear and excitement goes away.