So, I bought a new 17 inch MBP tonight. When it started up, it made a very odd sound that was similar to a CD/DVD being processed or ejected. I thought maybe it was a one time thing, but since restarting it a few times, it's made the same sound each time. Is this normal? I've never heard it before. It's like there's a CD or DVD in there, but of course there isn't.