Tail light fogging on my Prius v (lowercase v)

I have a 2012 Prius v (lowercase v for the Prius v wagon) and I've noticed that when it's very cold or humid outside the rear lights will have small condensation / fog inside the lense, just on the sides. Usually it clears up when the sun comes out or the temperature warms up.

Is this just because of the difference in temperature outside vs inside the car? Do I need new tail lights or do I need to re-seal them? I just don't want the moisture to start causing issues.