Low Total Cholesterol?

I recently took a pre-Life Insurance medical test that included urine and blood work. My total cholesterol was 139 which registered as too low. Is this something to worry about? I am a 24 yr old male, 5’9” 155 lbs. I am (obviously) not overweight but am not underweight either. I don’t eat poorly; I don’t drink anything with calories besides beer on the weekends. Are there other contributing factors to low total cholesterol? Is this indicative of nutritional deficiencies or general diet inadequacies?