Who saw a UFO?

Ok. This evening, I was relaxing in my pool, looking up in the sky, when I saw an airplane flying about 35 to 40 K in the sky, with a bright white dot following it about a few hundred feet behind it. The white dot slowed down and the gap between it and the plane got larger and larger. Then the dot disappeared as the plane kept on going. I don’t know what it was, but this was definitely unidentifiable. What the heck was that? (FYI, I am a licensed and experienced pilot.)