i was surprised too.
it was weird.i had my car in at garage to get gearbox fixed and when it came out it had this strange noise coming from it,so i took it back thinking it was the gearbox but the mechanic said it was the bearings.when he was putting it in nuatral the noise was still there so he said it couldnt be the gearbox,must be the bearings.the sound def wasnt there when i took it in when it was getting the gearbox fixed but was there when i picked it up.
the car hasnt been driven hard and its only done 50k.i dont understand it either.