Let me give you two examples.

1. A gf of mine was surprised when I found her at her job after her work hours. She had told me her office hours, and invited me to come by whenever I wanted. So when I get there she looks at me and says “How did you know I was here?” I thought to myself, should I tell her about the GPS I implanted on her in her sleep but thought she might think I was serious.
2. A co-worker of mine was surprised when I found him the bathroom at work. It wasn’t the normal bathroom that I went to, or him but it was close so why not? He said “How did you know I was here?” I said “It was random. I was hoping you weren’t here.”

Why are people paranoid? Things are going to happen like this when you are around someone enough. I never ask anyone who happens to find me in the bathroom, “How did you know I was here?” I don’t think anyone is following me. Maybe someone is and just good at hiding it, but I doubt it. My life would bore them to death, although its great for me.