I have one yearling that every single shed she has, you'd swear she had an RI. She whistles like nuts and the first few times it did really scare me. It isn't an RI though with her, it's just some sort of excessive shedding noise as the loose shed comes off her heat pits. She's the only snake I've ever owned that does this so loudly and consistently and she is definitely the oddball of the collection this way.