Have a2013 CTS Cadillac and the headlights fog up on the inside of the headlight assembly. GM says this is normal, but it appears to me to be a safety problem. It also might create future electrical and bulb problems.
Is anyone else having these problems?

Welcome to the forums!
Inside fogging is general caused by a crack/poor seal, where air/moisture is able to enter the assembly.
Would recommend you remove housing, inspect carefully for a leak, and apply a polyurethane sealant to any areas of concern.

The moisture inside the headlight housing will not harm the light bulb or the electronics. The wire harness is sealed to the bulb socket.

Moisture inside the headlight housing is consistent with it having broken headlight seals.

According to what I have been told by General Motors on their customer service telephone line the headlight assemblies are vented. They are saying that most late model GM cars and trucks have vented headlight assemblies and that moisture inside of them is normal. The dealer quotes GM and states that inside fogging is normal and the best way to get rid of it is to run the motor and have the car moving. In the same bulletin they repeat that when you run the car the fog will disappear in 2 to 6 hours normally.
Doesn't make sense to me and most of my friends have never had this problem. Just wondering does anyone else have this problem and how was it solved when you have vented headlights.

Fogging or condensation in headlights is normal, but if its there for days then you have a crack in the housing, the only reason ur having this "fog" is due to moisture in the inside. Sometimes you cant see the water due to it being under the reflector inside the housing.

Remove the headlight bulb from the housing
Remove the headlight assembly from the car and turn it lens down and hold it up, if water is in the housing you will see it.
Check the lens for cracks even small/tiny ones..
Also check the seal, u can as a just incase measure clean the seal and do a coat of sealant over it.