What are the chances

Today, my one night stand (and father of my baby if I am pregnant) walks into my office. I work for a newspaper and he was placing a legal notice. I haven't heard from him since we slept together. He said he meant to call me and was unaware I called him. Supposedly he dropped his phone in water and has a loaner phone. We talked about going out again this weekend. But I didn't tell him I could be pregnant. What are the chances that this would happen?