Sorry to resurrect an old thread, but I thought I'd bring closure to it.
I know what you guys are saying and what they meant; a mechanical over-rev is implicated. However I never miss a shift. Ever. I would know if I did. Hell this car was just a family car/grocery getter for me. I've been driving manual transmission cars for 16 years.
After the new motor self-destructed the same way (NO over rev of any sort, never went over 5krpms ever) and Mazda denied the warranty a final time, I traded the car in with the busted motor and absorbed the neg equity myself.
I did months of research and come to find out, the car had previously had a service performed before I owned it where a timing component was replaced along with an ECU flash. The definitely tells me that the car had a pre-existing timing issue.