Mine does it too, maybe once every 15 starts. I thought a starter would be more of a metalic higher pitched grinding noise, not an almost belt like squeal. I am not 100% on the starter being the culprit.
I have the same issue and had the dealer listen to it, he said it was the starter not disengaging from the flywheel. Mine will only do this on cold starts, once I'm well up to temp, it goes away....
__________________
"It broke because it wants to be Upgraded "
2012 Porsche Performance Driving School - SanDiego region
2001 Boxster S, Top Speed muffler, (Fred's) Mini Morimotto Projectors, Tarret UDP,
Short Shifter, Touch Screen Dual Din Radio, 03 4 Bow glass Top (DD & Auto-X since May 17,2012)