Alienware Alpha fan nose

I recently purchased an Alpha and I am highly impressed with the quality thus far. I only have one concern and that is whether or not the amount of noise the fans make is normal. I've read in every review that's the fans are whisper quiet, but my fan has an audible hum when idle. It fades out at higher fan speeds closer to that of what I am used to hearing from computers. I was curious if I have any need for concern.