The gap may be annoying but it's not going to cause you to come to harm. If you just really hate it aesthetically a heat sink might be of use. It's going to make your mod profile taller, and there may be cheaper ways of "obscuring" the gap using homemade methods. Best of luck, some mods and atomizers just don't sit quite flush on occasion but you should be perfectly safe, even if you don't use a method to "deal" with the gap.
Best of luck,
Anna