I have noticed that by monitoring iStat, the left fan of my base model rMBP typically runs at 150-200 rpms more than the right fan. I was wondering if this was an issue or potential issue. So far I don't think I have had any problems cooling the machine, but I really don't know if this is normal or not. I have noticed it in all situations, on and off the battery, on my lap and on my desk. It doesn't really seem to matter what the situation is, it does it when it's cool and it does it when it's hot. Thank you everyone and I apologize if this is just a silly question.