You can always diagnose a belt squeak by spraying some silicone on the belt, if the squeak goes away you will know the belt is not in alignment. Also, usually the belt with show some signs of fraying. Inspect the belt it if is frayed at all then you just need to realign the Pully. Is it worse when it rains or right when it stops raining? Water usually makes it worse.
After listening- It doesn't sound like belt squeak to me (I could be wrong though), it almost sounds like bearing squeak. You can spray a little silicone on the pully and if it doesn't go away it is likely alternator bearing. I think it is a good thing you are taking it to dealer.
Actually, scratch spraying silicone on the belt, just take it to the dealer. In general you can diagnose that squeak in that way but since you are taking it to the dealer anyway no reason to mess up your pully. Besides it is always a temporary fix anyway, the belt will always go into squeak again "If" it wasn't in alignment or loose.