Not technically wrong but kind of an asshole if there's a ton of cars they're holding up just to go 2 mph faster than the guy on the right of them. Maybe step on it a bit to get past him and clear the lane then slow back to what they want to go would be a good compromise. Where I used to live the law was actually that you had to pass within 1/2 a mile if you where in the left lane which I thought was pretty reasonable but I never witnessed that be enforced.