I have experienced this as well, and am currently. My right lung was doing this about last year this time, and over time, it went away. Now currently my left lung hurts when I breath in all the way, and hasn't begun popping yet, though I'm sure it will once it gets worked around long enough. I really don't think its something to worry about. I have had this thing happen a pretty long while now, and no negative side effects have come about, except for a little pain right off. If it were me, I would just forget about it. Besides, I think its kinda fun popping it haha.