The gasket may be one of the cleaning and maintenance items you are forgetting on your Big Green Egg, Kamado Joe, or other ceramic grill. The gasket is a key piece of your grill that keeps it operating properly. The upper and lower gasket on your dome and base seal your grill and make it fairly air tight. This ensures that the only air getting in is through your bottom vent and the only air getting out is through your top vent. If your gasket isn't sealing properly you can suck air into the grill and let smoke out. Signs of a bad gasket include uneven surfaces, thin spots, and a general look of wear and tear.
Luckily changing your gasket it really easy. Check out the video below and see for yourself.