I have now owned my rMBP for two weeks and have been monitoring the system through iStat Pro. Each time I check the fan speed, the left is about 160 rpm faster than the right no matter what speed they are at. At idle, the right fan is 2000 rpm and the left fan is 2160 rpm. This is my fourth MBP and all previous models have spun at nearly the same speed. Is anyone else noticing this problem? Should it be cause for concern?