Surfactants are components of all latex-based paints. When such paint is applied in cool or humid conditions, the paint film may take longer to dry. As a result the surfactants leach to the surface, causing color variations or shiny spots. This occurrence is common especially on bathroom ceilings.
Since these spots can be unsightly, most people will want to remove them immediately. Since the paint has not cured yet, you must avoid any vigorous cleaning action. Gently wipe the area with a sponge dipped in plain water. After cleaning you may find some more leaching, so it is recommended to wait for at least a week for the paint film to cure and the spots may disappear on their own. If they still persist, use a mild soap solution to wipe the paint film.
Avoid painting in cool or humid weather. Avoid using the shower when the paint film has not completely dried up as condensation of droplets on the film may draw out the surfactants, resulting in spotting.