I have a yellow spot on mine as well, I didn't show it to the dealer because I thought it might possibly have been caused by me. I do however have issues with the headliner not being glued down properly around the sunroof opening, and being lumpy there. I showed the salesperson, and compared with another on the lot. The others were lumpy as well, but were glued better, so I think they will fix it.
Mine is one of the old ones, built in Feb.
Does everyone with a sunroof have a lumpy headliner?