One explanation is that someone tried to use the exploits in a less than inconspicuous way, which resulted in a crash, and then Microsoft's crash reporting pick

One explanation is that someone tried to use the exploits in a less than inconspicuous way, which resulted in a crash, and then Microsoft's crash reporting picked it up. I read somewhere they specifically look for exploitable crashes (e.g. buffer overflows) in the long tail of rare crashes and try to fix them. But I'm just speculating of course.