Yea it's probably the HD. I've also an heard the occasional weird noise somewhere in the upper right part of my MBP, but it went away when I put in a second HD, so it was probably the optical drive. I've had no problems though before or since.
Maybe try popping off the back and see if it needs to be cleaned. I know its new but mine was too, but I was surprised how much dust was in there.
You could also do a Hardware Test (hold D before the gray start screen) just for peace of mind.