Kick?

Here I am sitting at the computer, watching a show on the Internet (we don't have cable), when all of a sudden I feel a little tap in my right lower abdomen. My first thought: It might be a muscle spasm or the pulsing of a blood vessel. I put my hand over the area and concentrate. Thump! There it is again...and again...and again. I think I just felt the baby move for the first time!