Corner of My Eye

I was at my grandfather's house and My parent's ran out with them, because we had ran out of Milk or something. I was all alone doing the dishes since we had just had breakfast and had my earphones in. I took them out because I got paranoid.

I went into the living room and turned the TV on so I could listen to something, then went back to the dishes and I picked up one of the pots. I turned around a little bit to hear the TV better and I saw something out of the corner of my eye.. It was Like an albino looking creature in the doorway. I jumped and i dropped the pot, covered my mouth, and I just kept staring at the doorway. I didn't get a good look at the creature because It was gone the a second. What I really noticed was it stood on all fours and it was completely white. It actually looked a lot like Gollum from Lord of the rings.

I tried talking to my parent's about it but they said it was just something I just imagined. If I imagined it then why did I jump at the sight of it, and why did I not get a better look at it? I can't be in that house alone anymore.