The lamp should dry out after a few minutes of operation. The lens may be upside down. The PIAA name must read right side up so the vent on the bottom can drain. Loosen, then re-tighten the screws. The gasket may be twisted or pinched.
Some gaskets have a vent gap.
Make sure it's on the bottom. 9O Pro lamps have a vent on the back of the housing in the center. The opening must be facing down. Water leaks through an obvious gap in the sealant or from a loose lens are defects covered under warranty. PIAA lamps are designed to function properly mounted upright or upside down, as long as a few details are taken into consideration.