What should I do if dust or a bug lands on wet ceramic coating?

If the coating is still workable, gently lift the particle away and re-level the area with a little fresh product and a clean towel. Avoid pressing down, which can drag the particle across the surface. If the coating has already cured with the contamination embedded, a light polish of that small spot followed by recoating is usually needed. Working indoors in a clean, low-airflow space reduces the risk.