A coworker noticed my fingertips turn yellow, I rubbed my hands together and they went back to normal in a few seconds, but she's concerned. This happens a lot, usually when I'm cold, but I'm always cold. I have extra heaters at my desk & at home keep the thermostat set at 78. I've mentioned it to my dr, but he wasn't concerned so I left it at that. Should I be doing anything about this? It does seem to be happening more frequently.