I call that "Highway leapfrog." I have found that there are some people who, I guess, are competitive, and they don't want to be behind me, but they don't want to go as fast as I have my cruise control set to, either. Usually, if I just stay in the left lane until they are barely visible in my rear-view, then they don't cut me off any more after that. Unfortunately, these days most states have laws about not using the left lane except to pass, but, what are you going to do?