Merc prop defect in casting?
 

I have a 30 bravo and when I took out the hub to use on another prop I noticed the factory casting has some holes in it. One goes through about 1/4 hole (with the hub in very hard to notice)

How could this get by merc quality control?

Or is that fairly common?

Safe to use?

What could happen? I assume crack and loose the ability to turn it?

Lets see some pictures. Hard to picture what you are describing.