The iPhone GPS uses a combination of information from GPS plus triangulation from known cellular tower locations and a database of wi-fi hotspot locations to determine your location (see http://support.apple.com/kb/HT4995). Not sure why this is happening with your wi-fi but if you moved your router to a new location since the database was established it may be using inaccurate information for triangulation. (This approach assumes that wi-fi hotspots rarely move.)
So when I say at home, I really mean at home. I am sitting at my house, on WiFi through my Airport Extreme, with internet provided by Comcast.
I did know about the triangulation already and database but was thorougly confused that it would think I am in LA...at least, hit a bigger city nearby like SF.
I don't think my router stores any info about location, plus i have been here at this house for over 5 years now.
Just didn't expect it to work like that.
Yes, location services are on and I have my info entered in for Siri.
Maybe just a hickup in the system. I recreated it about 2 to 3 times before posting. Will see how it works tomorrow.
Seems to be an issue with my internet connection. So far Siri now knows where I am. However, I noticed that the home page of Yahoo thought I also was in Los Angeles and I had to manually select San Francisco. So there might be some weird way my internet get routed that a program that uses that for location awareness thinks I originate in Los Angeles. Maybe Siri used this too a couple of times.
Just the age old problem of garbage in garbage out.