I always try to think they can't see me. The odd part was I had been gainig on him for some time. When I got near him i accelerated slightly because I don't like to ride beside them for any length of time. When I got halfway past he just changed lanes.
It's one of those times when I am glad I was really thinking about what to do if it happened when it DID happen.
gas it, push right, horn, push left, raise hand with finger!