Sounds odd but let me explain. I have a few pipes that will gurgle after maybe ten minutes. I gently blow back through the stems to clear them and voila, dry the rest of the way, no need for a cleaner. Could this be from the warm smoke condensing in the still cool stem ? Grasping at straws here. Any ideas what's causing this or better yet how to fix it ? Not a major issue but I'd like to fix it if I can. I've already opened the airways on these pipes and it hasn't helped.