Maybe she made some contacts here after they were done filming the SF episodes. Or maybe she used a Las Vegas connection (several Bay Area restaurants have Las Vegas branches). Or maybe she's just visiting and likes the Bowl (where they did at least some of their shopping).
ETA: according to wikipedia she is currently the executive chef at Todd English's brasserie, Riche, in New Orleans. There was also a report to that effect on our very own Chow.com (a Grinder posting that included a comment that if, as Tiffani claims, all her compliments to the other contestants ended up being cut, then apparently they aslo ended up on the cutting room floor in the other contestants' minds -- LOL!).