The other evening just after starting and putting the lights on I got a nasty noise from the engine compartment. A mix of auxiliary belt slip and a metallic grating that rose with revs. I sat contemplating going to get my other car for around a minute or less when the sound stopped dead and hasn't come back so far. The belt was new around 1K miles ago.
Any ideas? I thought the bearing in the alternator had gone but a worn bearing wouldn't instantly silence itself in my experience.