I bought helix LP headlights for my gti and they were doing the same thing. It wasn't water getting in, it was just the dew point of the air inside the headlight like everyone said. (Although still shouldn't happen on a new car) After many trial and errors, I blocked off the vents, sealed the access covers better and made calcium chloride desiccant packs and put in both headlights. It's been 6 months, fog free.
The problem with silica packs is they absorbe very slow and if it gets cold out, forget it. The other issue with the silica is once it's saturated, it will actually give up the moisture it absorbed if it gets hot enough outside.
The problem with calcium chloride, once it's saturated, it turns into a brine solution. However, if the headlight is totally sealed, and you're confident that there's not water getting in and you put a big enough pack in, there's not much to worry about. I check it now and again, calcium chloride can hold 80% of its size in water and will not release it back into the headlight. Also, it absorbes incredibly, hot or cold, keeping the air inside the headlight dry.
This shouldn't have to be done with new headlights / car, but just my $.02, and something that works for me.