Experts generally agree that drinking caffeinated coffee after a meal (large or small) can have both good and bad effects. The good effects include helping aid in digestion and metabolism and in regulating blood sugar. The bad effects include, for some people, an increase in acid reflux and heartburn.
Additionally, studies have shown that caffeinated coffee interferes with iron absorption by the body. This interference happens with iron sources found in plants but not in animals. Some women have a little trouble getting enough iron in their diets. If you are one of these women, I would avoid drinking coffee after a meal.