I think some wear is given with any lapping plate or stone by the nature of the action involved with lapping. Unfortunate that so much degradation happened, hopefully it gets resolved well.

I also have noticed my D8C has a bald spot in one corner now, I think partly due to me not knowing that the glass side of the shapton stones wasn't the side to hone on ... the DMT did, however, completely flatten the glass bottoms of my shapton ceramic on glass stones when I lapped them, unwittingly.