A friend of mine and I went to a ballgame over the weekend, and I noticed a big sore on his bottom lip. He said it was a cold sore...fine. So we were sitting watching the game, and he stood up at one point and I looked up and said something at which point he laughed and I felt a drop of spittle land right on my lips. I tried to keep a poker face, but eventually brought my arm up and wiped my mouth. It was literally just a drop, but is that conceivably enough to transmit the disease? Was wiping it with my arm a mistake, as it may have "pushed" it deeper into my lips? Or should I just relax?