you are right in thinking that it has in fact an orientation sensor - if this is the noise I´m not sure and even doubt it as I would not expect it to be very mechanical.
Anyway - noise seems normal.
Regards - MacSass
Ah I kept scrolling down, and finally somebody beat me to it. Mine rattles too.
Here is what it is:
There is a little ball residing inside of a small cavity. The camera knows which way it is turned, and thus which way to orient the picture, based on where the little ball is sitting.