MacBook making noise when turned on

[emigs]

I have a 15in unibody MacBook Pro. It had recently been taken to the the genius bar because I couldnt backback using timemachine. They had supposdly fixed but never told me what had been fixed. When I got home I turned the computer on and it sounded like the fans were hitting paper. I took back to the genius bar and told then that I had just gotten the computer back and it sounded like something was wrong with the fans. they took it once again and when i got it back a couple of days later everything seemed fined but I also dont know what they did. Well it's been a month and for the last week whenever I turn on my computer or start it again after its been asleep the fan against paper noise comes back. It doesn't sound as loud but you can hear it in a quiet room. Anyone have any idea what this could be? Im about to take it to another genius bar since i've lost faith in my usual apple store.