I just updated New Vegas, and just got out of Vault 22. I killed the 2 Giant Matsises that were out there, then got surprised by some Cazadors. So I used my VATS and noticed that the Cazadore had Zero health. I thought it would be dead, but it continued to be alive and killed me.

So I reloaded and avoided them. So how come all 3 Cazadors had Zero health? Not sure if this was a bug or not. Just letting Obsidian and Bethesda know.