No, not the whole rebooking for free thing.
Cheap fares often earn next to no miles but if there's a schedule change or a weather cancellation, sometimes the agent will rebook it into a higher fare bucket. Since it is now “qualifies” as a more expensive fare, the flight will now earn more miles than it previously would have.
So next time it happens, check the new fare class, and using the WhereToCredit calculator, find the right program to credit those miles. Silver linings!