Generally a fan like that is brushing against its own housing due to misalignment. That or it's cable got lose within the housing and the fan blades are hitting it.
Worst case that friction will reduce the lifespan of the fan and one day it will stop working. Won't affect the console other than being unable to manage airflow as well as it should. May cause the internal components to get a few degrees warmer than they should.
http://i.imgur.com/R15aJJ3.png http://i.imgur.com/NJqp6LS.png