Random instant crash when plugging in iPhone as usb tether

Thought I would share this as I have never seen this happen in all my time using Macs. I upgraded to Mavericks recently on a DIY Fusion Drive (1.5tb 2008 alu Macbook). So far all is running well until a glitch tonight that was bizarre. I plugged in my iphone 4 to use the internet via tethering. The battery died on the phone, so I unplugged and plugged in my wife's iphone 4S. The computer instantly crashed and restarted. No grey screen of death, no warning. I checked the console - I would paste it now but I haven't been able to find it since the log rolled over, but it was basically registering the usb tether, no threads on kernel panic etc and then it was a huge block of @@@@@@@@@@ for a page or so and then restart threads. Any ideas?