A quick update on the store snake, he got a vet apt this past monday and I heard about it today when I got in for my shift, apparently the vet said it's not an RI! They didn't do a bacterial culture, which I really would have preferred, but from a physical examination they said it wasn't an infection - I'm not sure whether to trust them on that or not, a culture seems like the most definitive way to tell for sure, but I'll be keeping an eye on the snake for the next few days to make sure.

If it's really not an RI, my next best guess would be shed around the mouth/nose making the whistling sound I heard? He was looking pretty crunchy when I first heard it, and he's had a history of bad sheds so that might have been it. I'm upping the humidity as much as I can to help with that, and the store protocol is daily soaks (even though that's gotta be stressing him out, but it's almost impossible to keep humidity up in the tank we've got). Either way I'm really hoping the vet's right and it's not an infection.