Do all MacBooks/Macs do this when they turn on or do I have a problem?

When I usually turn my mac on right before the chime that it makes with the apple logo i think its my dvd/cd drive thingy that makes a small grinding or buzzing noise. Then the chime comes in.. the only other time it does this is when I export stuff on GarageBand. Does all macs do this or should i seek help? Thanks!!!