My knowledge of aerodynamics is limited, but I would think that if the lights introduced a little turbulence into the airflow just before it passes over the radiator, that could be a good thing. Turbulent flow over a heat exchanger is (as far as I know) always superior to laminar flow in terms of heat transfer.
If the lights were causing some of the air that would've otherwise flowed across the radiator to instead go over the hood or around the headlights, then that is a different and probably not desirable situation. Trying to figure out which scenario is actually happening would probably be difficult though.
"I predict future happiness for Americans if they can prevent the government from wasting the labors of the people under the pretense of taking care of them" - Thomas Jefferson
"We all dream of a world filled with sunshine, peace, and happiness. The problem is that half the people think this sounds like a wonderful place to live...while the other half think it sounds like a wonderful place to pillage."