I'm going to go against the grain on this one. Low humidity is just as bad as too high of humidity. I bet your humidity is in the 30's or less. That's typically what my room is. I keep my snakes at 55-60% and mist to 70+ during shed and have never had a single issue. I'd keep humidity at least at 50% and I bet it will prevent the rest of your snakes from following the same route. Slightly higher temps and a humidity correction might fix your problem. Good luck!
Regards,
B