As long as it's not stressing the other one out really bad, and you'll know that by if it quits eating, colors become dark to indicate stress, or it's fins are torn and it's missing scales. In my 220 mixed school of pbass, my Pinima is the dominant guy. He keeps all 6 temensis and 2 piquiti in check, he will go around and bump into them from time to time just so they know he runs the tank. It's nothing serious and it's not all the time, just occasionally.
Since we can't see what's going on you'll have to be the judge as to whether seperating them is necessary or not, if it gets bad (again-missing scales, torn fins, not eating) then yes seperate them, if it's just chasing and nothing more you should be fine.