Bullies and Helicopters

So my kid has started talking down about preschool. Which is really unusual. When I questioned him , he talked specifically about two kids who "always want to fight". Sigh. So the question is - what is the right thing to do? I have no interest in being a helicopter parent that I saw so much of those 3 summers at Boy Scout/Cub Scout camp. Because those kids were major wankers. But my child is 4. And the reason he doesn't want to go to school because he doesn't want to fight. I can't let him get bullied if that's what is happening. After thinking about it for a while, I decided to talk with his teacher to get a better picture of it all. And as she put it, there are three children who are "quite a bit more aggressive with their play than the others". Read - there are 3 kids who are rough as hell. And then she mentioned that C-man's "newfound friends" are those who aren't so aggressive, but collaborative. Which is interesting to me. Because if you've met my child, he's not the silent, pushover type. At all. But apparently he's not into pushing and shoving and verbally taunting others. Which I have to say makes me a little proud. I'm so very glad he's not the mean kid. But it makes me so sad that by 4, that there are already bullies. I am just thankful for now, it's not my kid!