Are you sure your candle-lighting times for Palm Springs, CA are correct? The times provided on the Chabad.org candle-lighting times page seem to be a half hour off other California cities. Please advise.
Yes, Palm Springs has special rules with regard to when Shabbat begins. This is due to the large mountain which is directly west of the city. I've been there for Shabbat myself and I can tell you that it does get darker there earlier than cities nearby.
Although "sunset" may be a while later, Shabbat begins based on "visual sunset" not "actual sunset."
All the best,
Chabad.org Development Team