haha no way, i get that clunking noise too!!
to me it sounds like its just something that happens when i shift from P-D or just in those low low speeds.
i believe it may be normal, my first e92 m3 i had for 3 years and 81k miles, and it did it since day one and never had any probs.
my new one, has only 28k miles and its periodically makes that sound.
i think youll be fine, however, getting it checked out wouldnt hurt either.
2009 E92 M3- basic mods, future track car.
2011 Subaru STi daily driver- Stock, for now...