Why did my heart flutter multiple times? Should I be worried?

Palpitations. These are caused by many things. Stress, excitement, irritants both physical and chemical, pressure like a hiatal hernia or esophageal push or pull, and primary heart things, the causes are very many in number.
Palpitations. Are common and usually not much cause for concern unless symptoms result...Stress can be a major cause.
Best to get checked. People feel their "heart flutter" very commonly. And when no other symptoms or cardiac diseases are present, this is extremely rare to be something serious. Many times it is not even the heart you are feeling, rather the esophagus peristalsing or being dilated by gas, or chest muscle fasciculating. If you have dizziness, chest pain, shortness of breath, or fluttering lasts long, always see doctor.