If there's any sort of strange sound anywhere near the alternator I'd pull it for a look-see. If it's sounding 'coffee grinder' then I'd be pulling the alternator straight away - it should take well under an hour to get it out, check and put it back, including having a cup of tea....
Alternator check procedure with standard seat -- remove seat, remove any side panels and alternator cover, disconnect battery, remove ECU, remove battery, unplug alternator and remove 3 bolts, pull out alternator.
To replace -- line up alternator drive (there are usually cast nubs on the outer of the cup that line up with the dog fins), push alternator into place (some silicon lube helps here with new rubbers), put 3 bolts and plug back in, refit battery and ECU, THEN connect battery, refit panels and seat, go for a ride.
A lot of people seem paranoid about unplugging the ECU, in the course of my fannying around with mine I've unplugged it maybe 8 times since I bought the bike - disconnect the battery first and there's really no reason why it should cause any problems at all unless you force something.
I had no strange noises (that I noticed, I hadn't had the bike long) and one day the battery light came on. It still got me home, but it cut out as I pulled up outside my front door. Here is what I found.

and

The rubbers are pennies, the alternator cup isn't a huge amount, the driving dog is expensive for what it is.
Of course, it could be your starter being 'driven' because the sprag clutch is sticky. Pulling the starter should add less than 17 minutes to the above procedure if you are pulling the alternator anyway.