Try a hair drier instead of a heat gun ... less heat may work and is safe. You might also try sraying the joint with WD-40 first and letting it soak in then try the heat. If all else fails, treat yourself to a one piece stick.
Good Luck !!!!
If the joining sufaces are metal, liquid wrench will help. If fiberglass or carbon use WD 40 as Tat says!
Next time you join the rod rub the male end on the side of your nose and that problem will go away. Do so every time you assemble the stick.
gone fishin I agree with the nose junk trick. I have done this for years with every two piece rod. It does work like a charm unless you have a crispy sunburn.