Are those photos of that AC/DC playfield real or someones gee-up with photoshop ? 

If its real, I reckon STERN would replace the playfield in a heartbeat unless someone has used caustic chemicals on the playfield etc. I cant see the cannon causing that damage so quickly unless the balls have some sort of major flaws/pitmarks/rust or something terribly wrong ?.
The cannon side of the playfield has no reason to wear in that area at all, so i cant see how that area has been affected ? very weird ?

In any event, STERNS warranty process will take care of it.  I have checked my playfield tonight and the clear is well laid on. Time will tell if there are any other issues out there. Thanks for posting.