Defensive Driving

While waiting at a traffic light the other day, I glanced into my rear-view mirror and saw the driver of the truck behind me looking down and to the side. It seemed strange and I continued to watch. When the light changed I pulled away and noticed he was looking straight ahead. When a steady rate of speed was achieved I looked back and he was again looking down and to the right. Hmmn, is he texting or reading something? He was right on my back and I became concerned - if I have to stop fast will he be able to stop? I moved slowly into the right lane, slowed my speed and allowed him to pass. I put a few cars between his and my vehicle. Gradually, I lost sight of him and continued to drive smoothly and listen to my soothing music.