Talking in sermons?

Some time back, I sent an e-mail to my younger sister, and she got upset with me. I let my older sister read it, and she said that it was because I preached to her. Also, I have this new Christian in my church who tells me that I am preaching to people. Now, my older sister tells me that I have a tendency to "sermonize." I don't get it. To me, I'm just talking with people in conversation. I try to make it a point not to start preaching at people, because I don't want to turn them off. If I'm turning people off by just talking in normal conversation, what does that say of me? I had this new Christian that I mentioned before tell me earlier this week, that I "act perfect." I don't get it. I'm not acting like anything except myself. I don't know why anyone would think that I consider myself to be perfect, or that I would act like I am. I'm FAR from perfect. On a scale of 1 to 10, 10 being absolutely perfect and without a flaw, and 1 being a total failure towards being perfect, I think that I might land somewhere around a -5. Who am I to preach perfection, act perfect, or judge people. For those that know me, I'm wondering, do I talk in sermons? I mean, I know how to put together a sermon. I know how to deliver a sermon. I never would have thought that I talk in sermons, except that some say I do. Would someone care to explain? I don't think I could figure this out on my own.