How am I still walking?

On Tuesday, I was rolling for the rest of class with another white belt. He attempted an achilles lock but he wasn't reaping my leg so I was able to sit up and there was almost no pressure and certainly no pain. I thought it was weird that he went for a leg lock, because we're white belts so we aren't supposed to do them (even though no one has told us that, I overheard my coach saying he doesn't teach them to us because of safety concerns)

So we kept rolling and he subbed me with a guillotine. We started up again and he put on a heel hook. I've read on here that this is a pretty dangerous sub because of all the myriad ways it can go wrong and cripple. Again, if I remember correctly, he didn't reap my leg, so I sat on him a little and there was some pressure in my ankle but not any pain.

(I know, I know, "Tap before the pain, when you feel pressure, dammit!" But when you're not expecting another white belt to throw one on, and then your thinking "is this a heel hook? Why is he doing that?" By the time I had realized what was going on, he had let go)

He let go and we went on rolling. (he's a cool dude, btw.)

Well, yesterday my leg felt kinda stiff, but that could just be my imagination because I have a tendency to worry about injuries.

It got me thinking about my old club, and how I'm really starting to hate it. One day the coach there was teaching heel hooks. He told us nothing about how far to go, when to tap, how dangerous they can be, etc. (which was a recurring theme, I now realize)

I got paired with a heavy weight who, when drilling, would take me down and crank the heel hook until my knee felt like it was gunna snap. It hurt so bad. Damn that place was dangerous as hell. That happened a bunch of times.

So how am I still walking around? Shouldn't I have permanent damage now?