Stranger Things. (Don't read this at night)

We used to live in a small two bedroom apartment and my four year old son would sometimes get scared and sleep in my room. One morning I was waking up but still in bed and groggy. I saw a man from the back in what looked like a black jacket walking from our closet to exiting the bedroom. I was convinced that I was dreaming so I tried to go back to sleep. My son who was awake by then said "mom, you're here". I looked at him and said "of course I am. Where else would I be ". "Then who was that walking out of our room? " my son said . I ran out to the living room to see if someone was there but no one was. The door was completely unlocked. I looked out in the hall and no one was there. I thought that maybe it was a maintenance man who let themselves in but they had a strict policy that I would have had to let in maintenance to do any work so that was an unlikely explanation. I still don't know who it was.