Well, I will say that the first explanation will be according to one's deep beliefs, therefore your first explanation that it was an angel.
However, if I had seen the same thing maybe I would have had a different explanation. Possibly I would have been terrified.
But I will tell you two times when I had supernatural experiences :
1. Once, when I was in my teens, I lived in a town which had an air-force base. One summer night I went up to the terrace and there was some sand there on which I lay down with my face facing the starry sky. I don't know if I was dozing by then or I was awake. About 100 feet above me I saw a triangular shaped object flying above me. It was softly lit with red, green and I think yellow lights. I don't know what it was or if I was dreaming.
2. The second time, I was living in a large house which also served as the office in which I worked. One night, there was no one and I was sitting in the hall and working on a computer. My back was facing to the staircase which led to the upper floor. All was silent. And then I heard feet pattering down the staircase, something like if someone wasn't wearing shoes. I turned and there was no one.