Doesn't surprise me at all that occasionally one crosses into CA. My brother and I came across a huge cat near Angelus Oaks about 6 or 7 years ago. It was basically 40 yards from us and once it noticed that we were aware of it, it took off. It was curious but I got the vibe that it was just trying to hold still until we passed.
I have done some serious traveling in Central America (Nicaragua, El Salvador, Panama, Colombia...) which both have healthy populations of Puma and Jags and one thing I can tell you from some of the local people I was talking to (mainly in Nicaragua, and Panama) are not concerned with Pumas, but are more concerned about Jags. What I gathered from the locals is that if you see a Puma you stand your ground just as we do here. If you come across a Jag you get the hell out of dodge. Apparently they do not get spooked very easily and are pretty bold. A guy I became friends with in Panama told me a story of these European girls had a dispute with the local hotel they were staying at and took off to find a new place to stay. They ended up taking a wrong turn and got lost. 5 days later they found their bodies with skulls cracked, chest walls ripped open, hearts missing, and typical Jaguar attack evidence. They have a bite force that can crush a skull like nothing. That is there go to method of killing prey. So that being said, if I was actively hunting in an area with any possible sightings of a Jag, I would go with a hunting buddy and my head would be on a swivel.