Hello Doctor. In The Past 2-3 Days My Husband Noticed

Hello Doctor. In the past 2-3 days my husband noticed a speck or two flow out during urination. Yesterday, a speck was collected on a paper towel and we noticed when pressed it appeared to be blood, but not dark in color. The urine is a stronger than usual yellow in color and he has no pain or discomfort in any way during urination. He is 62 years old, with a history of prostate cancer that was treated. He recently, about 2-3 weeks ago began taking vitamin D3 5000 IU daily. Yesterday he expressed taking 2 per day. He is under doctors' care, primary doctor and a cardiologist for aspirin regime, blood pressure medication, and a beta-blocker. How alarmed should we be?