Why do I get little twinges of pain for a split second sometimes in the evening over my heart?

Many possibilities. Chest pain can come from many causes including heart, lungs, esophagus, rib cage and others. Not knowing your age, health history, family history, smoking history, cholesterol level, and additional information specific to this pain, it is impossible to tell exactly what is causing this pain. Best to see your family doctor or internist for a definitive answer as to the source of your pain.