Funny thing I just noticed my retic making a funny noise when he would breathe last night. But, then he shed last night for the first time for me. And, now I don't hear it anymore. I did hear alittle something but I heard this same noise when I took out my male granite yellow anaconda. It was me my very own nose was making the noise I heard with the tic,lol. But, the noise from yesterday was definately coming from the retic. He made the noise when he moved around on the bed.
If your bp is making this whistle noise even after shed. Then maybe a quick phone call to the herp vet would be in order? I wouldn't think you would have to make a appointment for something so minor?