My one and only visit to SoCal many years ago, I heard that a lot. You won't hear that in the South, or in any part of Texas I've frequented.
Another odd thing to my ears when I was there--although this may not be specific to LA dwellers, since you just used it--they called interstate highways the freeway. Freeway is not a term I'm used to hearing. People in the places I've lived say "take the interstate," or "take I-10," but they won't say "take the freeway."
Yeah, I use interstate, too, but freeway and highway are common here, likely because 101, which is a primary road throughout California, is not an interstate (and, for some reason, interstates and 101--freeways--are not highways).
Yeah, there are a lot of CA state highways that are many lanes, and are limited access highways, but are (of course) not interstates. So "freeway" works. It doesn't require us to distinguish between the two. Especially since in SoCal or the Bay Area, it's not like you're crossing another state line in less than 4+ hours from wherever you are anyway.
And it's a contrast to the toll roads, which we also have.
