If he bumped your car, you should have, as already mentioned, taken his license number and called the police.
Be careful in the left lane..It can be annoying when someone is going slow in the left lane and wont move because they are going left in about 5 minutes.. I'm not saying him bumping you was right, at all, but the left lane is the fast lane so the cars wanting to drive fast theoretically should be in that lane..