Does it break my warranty to open the new MacBook Pro Retina?

I have a Macbook Pro Retina 15" and something is loose inside of the chassis... it feels like a battery cell or board of some sort. When I transport the laptop, I can feel it hitting the bottom aluminum cover. I took it to the Apple Store and the geniuses said they couldn't hear or feel anything, despite my demonstrating the problem. They also opened it and said they saw nothing loose. What's odd is that the "looseness" intensifies when the computer heats up, making me believe it could be a defective glue application on one of the battery cells.

I'm at the point of considering a return; however, I am interested in opening this up and checking for myself. I've worked on many laptops, including Macbooks, but never a Macbook with pentalobe screws. So my question, since Apple is trying to keep up out of this machine, am I risking the warranty by opening the case and inspecting? Second, if anyone has any experience with the inside of this device, I'd appreciate and thoughts / suggestions on what to look for.

Thanks!