While it is not strictly necessary, taking the time to cover and rest a pancake batter in a cool place for about 15-30 minutes to allows the starch in the flour to swell, will give a lighter result. If the batter is cooked just after being made, the pancakes will have a bubbly surface rather than appearing flat. But do not leave the batter to stand for more than 1 hour at room temperature or it may begin to ferment.
Batter left to stand for an hour or more may separate out. If so, just stir to remix. If it thickens slightly, thin it with some extra liquid.
** Asian Recipes