I Got theses disks a few weeks ago at costco for 2 100 packs for $32. out of the 112 dvds of them i have already invested in burning data to, all have verified with Nero and all seem to have good PIPO scans although my drive seems to vary greatly on that. One scan of a disk can get crazy PI levels at the end and a scan of the same disk without even ejecting is completely fine the second scan.
Heres the best I could do of getting a pic, thats actually a burned disk but it looks the same before its burned to. the rings are only visible and a very fine angel and you might not even notice them if your not looking. My guess is its just variation density in the die.