A common complaint from new Weber grill owners goes something like this:
It looks like the paint is peeling inside the lid of my new grill. WTF? I expected more from Weber!
OK, just chillax, Grasshopper. Weber does not paint its grills. They use a baked-on porcelain enamel finish that cannot peel. What you’re seeing is grease and smoke that builds-up during normal use, turns into harmless carbon, and eventually peels off in flakes or sheets.
Before grilling, use a grill brush or a balled-up piece of aluminum foil to remove any loose flakes. If you really want to be fastidious about it, each time you finish cooking, while the lid is still warm, wipe the inside surface with paper towels or a soap and water solution to prevent the build-up.