I wouldn't just take it apart and paint it now though. There could be a crack in the housing that you can't see. Heat and humidity find there way into the smallest places. Get it fixed under warranty then take the new one apart and do as you wish.
I took mine in for the same thing. The dealership gave me a print out that says GM is not sealing the headlight because it is cheaper to replace parts of the headlamp rather than having to replace the whole thing. So, some moisture is okay to them... even though it sucks have moisture build up inside of the light.
the place i bought mine form gave me no problems at all, and they ordered a complete new headlight as soon as he seen the light. the bad thing is that the headlights are on national backorder. i'm going to call gm customer care today and see if they can ship it asap for me.
i had actual water in mine though, not just fog from humidity.