How close was I to ping out?

You could possibly have a more serious problem. I don't mean to scare you but it's not that unlikely and you should see a doctor. A couple of years ago I fainted during exercise (it had never happened before) and saw a doctor and they ended up finding a heart condition that I have. I still live a normal life but there are plenty of conditions that are possible with fainting during exercise, and it's always best to just be safe and get checked out by a doctor.