Driving on the highway

Have you ever had the experience where you are driving on the left most lane and trying to go a bit faster to pass the very slow vehicle on your right? And Have you tried to get in front of the other 'speed limit maintaining' vehicle so that you can pass?

What typically happens is that the 'speed limit maintaining' vehicle all of a sudden speeds up in order to prevent you from passing... is this human nature? is it okay to drive a bit slower than the speed limit on the fast lane but go as FAST AS YOU CAN when you see that someone is about to pass you? Why is that? I can't help but wonder the 'human nature' that gets revealed on highway driving.