Notice the guy's email is at denim-tech.com
If you search his email on google, it shows that it's the same guy who operates denim-tech.
And if you search more further about denim-tech, I got this link
It says "I am the Director of Product Development for Denim-tech. I do wash design/developmetn for brands such as Rag&Bone, RRL, Simon Miller, Elizabeth&James, Edwin Japan, and Ron Herman just to name a few. I am also responsible for tranfering all development over to production and trouble shooting any production issues."
So the answer is that the denim-tech do make jeans here in LA.
Cool, so I guess I got some of their sample stuff. Denim-tech is owned by http://www.howa-net.co.jp/en/ who make equally awesome stuff in Japan.