Since the original posters question has been answered, I am going to take this a bit further and ask one here myself, as it pertains to this subject, so I dont need to start a new thread.
I have a 20 month old 13" MBP, 256 Ghz, 4Gig Ram, etc.
First Mac I have owned.
*Snip*
Completely normal, your computer will never, ever be at 57*F. You may want to change your notification.