is this normal?

is it normal for the optical drive to make noise when i first turn my macbook on...just got it not to long ago and im not familiar with macs...the first one i bought i had to return because it made a humming sound upon start up...they said it was optical drive, im guessing this is the same thing but it sounds like somethings starting...

My replacement optical drive did that on my old MBP still does according to current owner.

Yes, on both of my MacBook Pros, and even on my replacement drive on my second MacBook Pro, it will make a brief whirring noise when the machine is turned on or when it awakes from sleep. I believe this is germane to slimline slot-loading drives.