Should I Be Concerned For Bruise Like Spots On Arm?

Over the past three weeks I've noticed 2 bruise-like spots on my upper right arm. I only have seen this for about three weeks, but the bruises themselves only come one at a time, and vanish in about 5-7 days. I do not have any other symptoms and am in pretty good physical condition. I worry sometimes about my health, and these really bruises worry me because I cannot remember where they came from. Should I consult a physician or am I just overreacting? P.S. I have port-wine stain birthmarks on the right side of my body...the same side as the bruise-like spots.