Have you checked if all dustcaps are clipped correctly? Might also check if their rubber seals are all in place.

Maybe you should not bake open it just yet but you might check all around the seal between the clear front part and black back part to see if there is any apparent opening.
If you find a gap in the seal, your waranty should take care of this.

It is normal to have moisture in the headlight sometimes but never that much. Plus, if it never cleared out entirely, it might be a good idea to remove all dustcaps on a clear warm day to allow for that moisture to get out of the light (don't forget to put the dustcaps back on). From there, you will see how long it stays clear or how fast it gets foggy again.

 

Not sure about there, but at the dealership I work at here in Canada, they will try and reseal the headlight. And if that does not work, then they will replace the lamp under warranty. Maybe you should try your local dealership and see what they say.

 

The local dealership won't fix anything.

Looks like the dust cap had come off. I removed it and dried it out, and put it back. We'll see if it leaks next carwash.

 

That's WAY TOO MUCH moisture buildup in that headlamp! The fact that your other headlamp remains dry indicates a significant seal breach in the housing assembly. This can be caused by one of two things: either your headlamp assembly was defective from the beginning or road debris impact caused a hairline crack in the lens. If it was the latter, then Hyundai will not fix it under warranty. But if your problem began when you took ownership of the car (assuming you're the original owner) then Hyundai is obligated to repair/replace it under warranty because IT IS a defective item. Getting that much moisture intrusion from the back of the lamp assembly via rain or carwash seems highly unlikely.