I've had mild indigestion 3-4 times in the last week. what am i doing wrong? how can i prevent? is there something more serious i need to worry about?

Food allergies/acid: A lot of processed foods we eat causes heartburn, especially spicy foods and caffeine cause trouble with the valve between your esophagus and stomach. Others have food allergies or intolerance to for example lactose (milk products), or often these days, gluten. Watch your diet and see what foods cause trouble, then eliminate them from your diet if possible or substitute them. See your doc if worse.