Just got the car back. They replaced the bolts again and installed new diff just to make certain something inside wasn't locking up and causing it.
I feel the repairs were made under a bit of goodwill as the car is perfect, completely stock, still has original tires with lots of tread left with 14k miles on it now.
They replaced the bolts, another complete subframe, and installed a re manufactured differential to make sure something wasn't binding. Remember that the car performed flawlessly for 13k miles and then when the first set of bolts snapped, it happened again within 500 miles of the repair. So I'm being told with everything now replaced, "it better not happen again..."
The torque on these bolts must be enormous when the clutch and tires do not slip at all. I wouldn't attempt to drag the car, thats for sure. I'll now rethink the some of the high rpm, sudden "on/off" throttle movements as that surely must stress those things. I saw a picture of the subframe bolt hole and it was wallowed out by movement. I think once it gets enough "play", it just snaps. Thats my opinion, dealer didn't say.
Good luck all!