If the DM was close enough to "pop" her reg back in, she had a buddy doing the job. Why do people jump to conclusions so fast?
Also, the presence of a divemaster at all implies that she was taking a class of some sort, since groups out here generally don't dive with DMs.
It may have been a refresher course or a dive to familiarize herself with SoCal waters (and kelp) - but it might even have been her very first checkout dive. I had a few scary moments myself on my first dive (also at the dive park) - it's a far cry from getting certified somewhere in warm, clear water.
I'm having dinner tonight with some friends who were at the dive park yesterday; I'll post if they have any information to add.