I installed my pedals myself... I think I may have undertightened them. I don't have a way to measure the torque.

So then today my right pedal feels funny, and I'm wondering what's going on. Then it falls right off.

I am confused because the pedal threads were totally stripped. There were many metal coils coming out of the hole. I got special short crank arms that were tapped by hand, so I guess that was the insert to make threads in alumnium. I'm just wondering if it's more likely that undertightening somehow caused this problem, or the threads weren't tapped well.

My understanding is that if you undertighten the pedals, they should naturally tighten just by pedaling? This thread seems to say that: http://www.bikeforums.net/showthread.php?t=268330

I rode the bike probably ~10 miles with this setup over a couple days. So it failed pretty fast.