I recently brought a BMW Z3, it has a auto

I recently brought a BMW Z3, it has a auto steptronic gearbox. On The first few days of driving the car the 'Automatic transmission' fault light came on a number of times and the transmission switched to emergency run mode, The light has not come on since (about a month now). I had a system diagnostic run, which showed no record of the fault evident on the cars computer. Any thoughts on what may have caused this? Should I be concerned? The gearbox changes gear very smoothly in both auto or manual modes.