guitar causes bad circulation?

Well, ive been playing guitar for 2 months now and sometimes when I play a lot the dead skin on my finger will turn a little blue. Nothing too crazy, just a little area. I was wondering if this is a sign of bad circulation and, dont wanna sound ridiculous, but can it any way cause gangrene. I was just wondering because i read that gangrene can be caused by lack of circulation.  Please reply, thank you