Pain...is it all in the mind?

I've been aware of T's extremely high pain threshold pretty much since she started moving.  She's always been the kid who has to be really hurt to cry.  Things that make other kids sob and seek solace, only make her jump up and keep going.  I have this crazy fear that some day she'll need x-rays and they'll show multiple old fractures we never knew she had. 
Yesterday, I was in the front yard talking to my neighbor's daughter and grandson.  We just met them yesterday, and they came down to meet us because like T, L is on the spectrum.  The kids went inside to play a little.  I really wasn't worried because well, if our house is safe for T to be in, it's safe for anyone to be in.  Besides, the door was open and we could hear their every move.  That would lead you to believe that if one of my children was hurt and trailing blood behind her, we'd certainly know that immediately.  Apparently, I was very mistaken.  We were chatting about autism, and strangely enough, high pain tolerance, when T came out the front door and said she hurt her foot.  She wasn't crying, so I looked at her foot and that's when I saw the blood dripping all over the sidewalk.  I couldn't really tell where or what the injury was because her entire foot was covered in blood.  I asked her what happened and she told me she stepped on the dog brush/undercoat rake and, brace yourself, it was stuck in her heel.  I asked her if she pulled it out and her very logical Aspie self said, "Well yeah.  That's the only way I could come get you!".  Like I once again showed myself to be completely ignorant. 
I'm sure most parents would've been mortified to witness that whole thing, not to mention not wanting their kid to ever come over to my house again.  She actually remained calm and said, "Don't worry, this stuff is happening at our house all the time too."  *sigh of relief from me*
I brought T in cleaned it up more, got her to lay down so I could look at it, and got the bleeding stopped.  Through all that, the most she ever did was whimper that it hurt.  She never actually shed any tears.  I don't know if it really hurt or if she was just freaked out and thought that's what she was supposed to do and say.  I mean, it should've hurt like hell!!!  She probably sat and whimpered for all of five minutes before she was up and running around on it again.  It's bruised and has to be sore today, but she hasn't even mentioned it.  It makes me a little sick to my stomach to think of the possible injuries she could sustain as she gets older...