I haven't worked for Sephora, but a couple of my friends have. One worked inside JCPenney and one worked at a free standing store. When you work at the ones inside JCPenney, you work for JCPenney, not Sephora. One thing both of them told me is that pay is based on experience, so you can really negotiate salary there if you are experienced in cosmetics. I have always heard wonderful things through the years from people that have worked for JCPenney. And now, they have a new-ish CEO that is really revamping the stores and making them better. The only downside I could see is when they have extended hours during the holidays. JCPenney is open until midnight a lot during the Christmas season. Other than that, I don't know of any other negatives.
And yes, I think you should give her a phone call. :) Good luck!