The problem tends to occur after driving for 25-30 minutes, so most often on restart (clutch pedal depressed) after auto-stop.
On depressing the clutch pedal, there's about 1-2 seconds of screeching/grating as the starter motor kicks in. This doesn't sound great, but is intermittent, in that you can predict roughly when it might happen, but can't reliably repeat the symptom. We took it back to the garage who sold us the 3-year-old vehicle back in November, but they couldn't repeat it either.
It only ever happens a couple of times and then never again on the same trip.
It's obviously in some way connected to engaging the starter motor (yes, I know I could eliminate the sympton by switching auto-stop off!), but why would it only behave accoring to the pattern described and not at other times? How serious could it be?
Any ideas or suggestions (expecially from someone who has experienced this) wlecome.