Is it normal for my MacBook Pro (unibody) to creak in some spots?

Question

I bought a new MacBook Pro 15-inch model with highest specifications in this June. I also installed Lion and have updated it.

Moreover, I would like to ask somebody who already has the same model, or any MacBook Pro, if it is normal to hear ticking sound when you push some spots on the bottom of the computer (beneath where the trackpad is).