Ok, thanks a lot guys.
Seems like this is just a "undocumented feature" of the Mamba Max ESC, and it will not happen again, say, during a race, when I have a decent Lipo in there.
I just wanted to make sure my ESC wasn't broken or anything, as I've never heard of this type of thing happening before.
Edit: I'm still not sure how the Mamba's "Lipo Cut Off" and thermal protection features will function exactly. I guess I'll try turning on Lipo Cut Off next time and see how it reacts. But what about thermalling, will it shut off just like it does now from low voltage?