Probably something like that. The headlights would rattle when latched otherwise. The latching isn't all that rock solid, so a spring to keep the headlights tight against one side of the latch jaws would seem prudent. Theoretically, if you hit a speed bump or pothole, the impact could make your headlights dislodge from their latching and turn off or flicker. Added spring tension could possibly have been added to reduce the chance of this happening.