how can i prevent this?? i cant find any other thread on this, thanks

 

It's never happened on my lights.

Headlamp housing has vent tubes that are angled downward. In case you get moisture inside, headlamp operation will warm the housing and "vent" the moisture. If you've got a puddle inside your headlamp housing, your housing isn't sealed correctly or water is draining inside through the drain tube, which could happen if the tube is pointing upward or missing.