Undrneath my nails are a very light bluish-grey color. Could this be an indication of a circulatory problem? Heart problem?

Nail bed color. The color of nail beds is a nonspecific indicator of oxygenation of the blood and hemoglobin content. If your nail beds usually are pink and turn blue that likely is abnormal. If your nail beds have always been the color you describe, that may just be your normal color. If there is a reason in your history for concern, you should consult your doctor.