Good for another 100,000 miles

I was sitting at the reception area of the cardiologist's office today. My appointment to train him for the hospital's computer system was supposed to be at noon. He got called to the wards so I ended up waiting for at least 45 minutes. While waiting, I noticed an elderly man sitting across the room. I was reading my book, the one about reflections of women doctors, to pass the time. A few minutes later, in my peripheral view, I saw an elderly woman come out to the reception area. I heard the elderly man who I am assuming to be her husband say, "So, you're good for another 100,000 miles?". I looked up at him since I thought that his comment was really funny. He had such a warm loving smile directed to his wife. He glanced at me briefly, he must have noticed that I was also smiling. His wife didn't hear him at first so as he approached her he said again, "good for another 100,000 miles?". His wife laughed and they walked off to the sunset.