That could certainly cause the problem I've seen a handful of disks let go like that when they get near the end of their life. May be from abuse (dumping clutch) or that's just what decided to let loose first. I'm not sure it's that uncommon. That disk looks like it has a few miles on it.

Disk looks very OEM... but who knows.

So silly question... but you didn't notice that "missing" spring when you ripped it apart (post #1) ?? Just curious....