The main thing you should look out for is respiratory infection.

Signs of an RI include:
Open mouth breathing
Mucous or saliva coming from the nose and mouth
Bubbles around the nose and mouth
Wheezing, clicking, or popping noises
Face rubbing

If you notice any of these symptoms, take the snake to the vet right away to get treated. If an RI is left untreated it could very well be life threatening.

Just keep your snakes warm and keep a close eye on them. Raising the hot side temp slightly might help them resist the infection a bit more.