Depends on how much water is inside the headlight housing.
A little condensation is not a problem and will quickly disapate when the headlights are turned on. However if you see a puddle at the bottom of the reflector, you may have a bigger problem.
You can drain out the water by removing the Headlight assembly, remove the bulb and socket. Drain the water out and dry it gently with a hair dryer. Once it's dry and clear, check for any dullness or discoloration of the reflector where the water was puddled. If the water started to corrode the silver plating on the reflector, you probably need to replace the headligght housing.
...Rich