Yea, I was thinking about that when I was doing them. I did catch myself doing that twards the end of my sets.
The reps I missed (last one on the last 2 sets), I actually went up on my toes (bad form, I know) but still didn't finish the reps, I only got the bar half way up.
That's what I'm hoping. I've been using my belt less for squats and deads (though I used it for my 10X3 squat day monday).
Before I started doing CW's routines, I almost never did any direct ab or lower back work.