I didn't over tighten it. I used the arrows to make sure. But I took off the hubstack, and found the bolt rotated slightly, I think that caused the crack. So I am wondering that if I send it back, will this just happen again from unscrewing it? Thanks for trying to help.
If you just got it, contact where you bought it from and see about a return/exchange. I recently had a problem with a YYE order, contacted YYE, they're taking care of it for me right now.
When did you get this PGM? I got mine used a while ago. Can't find any problems with it.