but three on one machine? Be prepared for the possibility that the warranty claim might be challenged. You say "No accidental damage obviously", but I'm not sure why it's obvious. I certainly hope it doesn't happen, but it's on the cards that the manufacturer might say that so many cracks can only be the result of misuse of some sort. You don't say how long you've had this machine, and that will obviously have a bearing on matters.
I'm not aware of any particular problem with this model.