Do I have a ghostly friend in my house?

So every single night I sleep with my door open. This morning at 5 am I woke up and it was closed. I don't remember closing it because I like it open and I'm pretty sure my cat didn't close it, she's not smart enough:( So anyway I got up and opened it. I got back in bed and out of the corner of my eye it looked like my door was closed again but when I turned around it was open. Am I just paranoid or do you think there could be a ghostly friend in my room?