I have had my new pro since christmas, and it has been incredible. however i noticed from day one that periodically i get this buzzing noise coming from the left speaker - closest to the screen. is it the hard drive? what is it... and is it normal? sometimes if i tap the speaker area (next to the magsafe) it goes away.. and other times its pretty loud. i do NOT have applecare. should I purchase that as well. i guess this is a two parter. the noise - and applecare.