Just picked mine up last week and have not noticed any squeaking from the coilovers or springs. But I have noticed a slight rattle coming from the back seats at very low speeds between 5-20 mph.
As far as a possible solution, I remember reading a thread that was discussing a squeaking or clunking noise in the F10 M5 and also on the M6's that they were working to sort out and fix. I will try and find the thread and post for you.
Sorry to hear and good luck