Sometimes they don't get it all. Mineral oil, by the way, can be a double-edged sword. While it does soften the wax, if you don't do something to remove the softened wax it just hardens again, and in my experience if you get enough wax that you need a doc to clean it out, which I do a couple times a year, you really can't remove it yourself. If your ears show irritation when you get it done they usually give you a tiny bottle of ear drops for that. Sometimes the person cleaning the ears isn't very gentle at it and it can be very irritating and sometimes painful. Some have a very light touch and it's no problem at all. It's also very weird for a few days after getting them cleaned out, because by the time it gets bad enough to need a doc to clean it out you've had a stuffed ear for a long time. When it's cleaned out, everything is much too loud and the ear can still feel like it's full of wax for a few days afterwards. In other words, it's a bit of a trauma to the ears and also a big change. To last a month, though, is a long time, so it's a good idea to see a doc. You'll probably get some ear drops that might help. I'm guessing it's the pressure change and the pressure of the procedure, and it should have gone away, but we're all different.