My 7 year old sulcata tortoise whistles when he breathes. I’ve noticed it’s been going on for over a month and didn’t think much of it at first. He’s very active, has a big appetite, and overall seems happy and healthy. It wasn’t till recently I thought I’d better look into it since it wasn’t going away. Could it be a respiratory infection? I don’t see any discharge come from his nose. Is this something I should be worried about and bring him to the vet?