Why did my bedroom door slam shut with no one in my room?

I have been living here since end of April it is an old house. I don't have any windows open and no one in my room why did it slam shut?? I have asked the land lord and no one has died here. What could it of been? I am scared to sleep in my room now. My room does look like a master bedroom. I am being totally serious. It did not slam hard or loud but it was just made a little bang. I am not high.. I have never done any drugs in my entire life. Is the house haunted or something?