I would say, it may be that you were falling asleep, or corner of the eye thing happens a lot. I often see cats darting away just outside the field of my vision. I don't think they are hallucinations but I'm not sure.

Recnetly I also see a man in our house. He's a shadow man. He stands about the same height as my husband and the same build. He always is standing in a dark room and I'm looking right at him. It never is my husband, and it creeps me out! Because he just kind of... fades away. Sometimes I see a figure of a man peeking around the door of our bedroom, or like you say, he just walked through the door out of sight. But it isn't my husband or my kids. But those are always corner of the eye things.

I don't mind your posts. If you have questions or need help it is better to ask than keep it in, I say!