It does surprise me somewhat, but I can understand the central districts being primarily republican. My younger brother is a republican, and he's won an average of 63% of the votes for the past three elections to the legislature. His biggest win was in the mid-70s.
I'm pretty sure that the SF Bay Area where I live is predominantly democratic. Even the guys I meet at the coffee shop most weekday mornings talk the talk of Obama.
We also have a heavy concentration of Hispanics in our area as well as Asians.