A couple of years ago I received a CGC comic in the mail, I live in Regina Sk Canada and it was a typical cold winter day. The slab I received was a comic for my personal collection so it is/was cracked out. Brought the slab in "directly from the cold" and put a butter knife on the side to spread it open, usually a post breaks or the plastic cracks, the posts popped out perfectly and I removed the contents and they popped back together.
Not sure if it was the extreme cold and there was a possible contraction of the inner post or ?, but regardless it was undetectable.
Maybe they could have a fail safe system where they have the CGC cert# etched on the case somewhere to make sure that both numbers correlate