PVG-LAX- I'm pretty sure you would've gotten a different response had you asked, "Could you come back later for my coat?" On the other hand though, LAX crews are surly at best. I personally avoid going through or to LAX if I can help it.
SFO-PVG- Commonplace on North American carriers. However I get younger crews on west coast destinations and the really advanced ages on TPAC flights to/from ORD and IAD. YMMV with the crew I guess.