I know I only live in San Diego but, it is not a usual thing to take a walk in CA at midnight...even for L.A.
I first thought these two points you made were very odd things to have occurred. If anything, that is an hour you especially do not want to be out walking, even in Brentwood...unless you're out walking your dog. I've heard no mention of that so I think it's odd. FWIW
See post 82 ... it may explain the walking issue.