I'm not sure what parts they changed, but the work order says replaced mirror box assembly. I wasn't sure if that plastic overhang piece was there before. Since you say that yours has it, then they probably just super glued it and cleaned it 
Edit: Looking at the Service Details, here is what it says.
We have examined the product according to your request, and a modification was made to secure the mirror. The part was attached. Checked all, adjusted focus and exposure, cleaned to factory specs. Cleaned C-MOS