Whistle Breathing, Vet Not Concerned?

[Bogertophis]

You may want to consider also raising the temperature gradient in the enclosure as a whole by a few degrees. Cool side and warm side then monitor the reptile closely for any changes. Increasing the temperatures is believed to boost the animals immune system somewhat.

Agree, as long as you're not already keeping him at the upper end of safety- if that's the case- you could try slightly increasing the warmth on the "cool" side, rather than making the warm side "too hot" for safety.