Don't stress too much, but get it checked out. According to Dr. Bruno, bad breath is often a symptom of gastro-esophageal reflux disease, a condition where increased levels of stomach acid cause you to burp up partially digested food. Gum disease and tooth decay can also produce odors, as can bacteria buildup on the tongue.
Cut down on common acid causers such as coffee and spicy food. Floss daily, and gently scrub your tongue whenever you brush. If the problem persists, contact your dentist.