Witch, what size plates are you using for the pinches? I assume your terminology for 3x20 is three sets of static holds for 20 seconds. My gym has those rubber coated plates, so my plate pinch is a single 45lb plate without any grooves or lips to hang on to. I have to watch my toes!

When my grip goes, it goes without much warning.
Once you feel better and your strength is up to par, i challenge you to do some plate flips
For an extreme visual (jesse was a monster)
http://www.marunde-muscle.com/videos/jessepinchflip25s.wmv
I do them on a rare occasion which i don't do deads and chins (which blasts my grip anyways), except i only use one plate w/both hands and a wide foot stance to eliminate broken toes. I've found it helps when i get to a plateau on my deadlift, as it works your grip and lower back/hams depending on how you do them.