Does it have any smell now?
If they were to allow you to give it a couple weeks like POWERFREAK said that would be the thing to do if it doesn't smell at all now.
If there is ANY smell now, I would change it. It could get into all of the upholstery as time goes on.
As for the job and workman ship, It is a pain-in the but, however almost all of the work they do is and it should come out just fine. That is why people don't just do it there selves.
SS/RS, M6, MGW Shifter, GM GFX