Yes, I noticed that parts were lifting slightly when I tightened the vise down. I readjusted the movable jaw and the soft jaws. Then I started to load the next part. As I tightened the vise down I felt something let go, kind of like when a thread strips. That's when I noticed the crack.
I ordered a Kurt DX4 to replace it. I'm sure it will be much nicer than the CDCO vise.