Tim, just a couple of positive words to counter all of the *****-taking (not that I didn't have a chuckle when I read the story - seeing as you're OK and all). Don't fret it too much. LA is some killer traffic. I commute 30 miles each way in the SF Bay Area, lane splitting the whole way, and I'm a very comfortable and confident rider. On a trip through the LA basin over the weekend, on my way home from San Diego, I had 4 separate cars try to move into my lane on me without looking, signaling, or otherwise telegraphing the move. I was ready for it, and came out unscathed, but it made it clear that LA drivers are unf*cking believably bad drivers. 3 of the 4 culprits were on cellphones, of course.
Getting back to my point... You've been thrown in at the deep end, lad, and don't forget it. Take it easy and work your way into more aggressive riding on the freeways and streets of LA slowly. You'll only need a couple of weeks, but until then, I'd suggest you only lane split in stopped or barely moving traffic, and keep your speeds low to begin with and increase them gradually. As you get used to the mayhem, it will be harder and harder for things to surprise you.
One last thing, and this one bites a lot of newbies, I suspect. You are far safer lanesplitting BETWEEN two cars than you are with an empty space on one side. No one in CA signals a move into an empty spot in traffic, since anyone who did would immediately suffer the loss of the spot as the driver behind speeds up to fill it. Practiced drivers make a point of not telegraphing their moves, watching the gap move into position next to them in a mirror before slamming the wheel to the side and gunning it. Slow down and cover your brake whenever you are lanesplittting past a gap. In fact, I prefer to use a throttle rocker type device (plastic doohickey that lets you activate the throttle with the base of your hand) in order to allow me to keep the brake covered at all times.