Oh yes, the feared craters *lol*
Best way to prevent them is speed up the surface drying time. Try either a dehydrator, a fan, or my method: convection oven on lowest temperature. I hardly have problems with dimples anymore.
The warm air causes the surface to dry quick enough so that any craters are under it, where you cannot see them 
But don't overdo it, too much temperature will cause butter-bleed!