Corroded calipers 09 A8L

[Daggerpie]

Gents, I'm after a bit of advice, I just noticed the centre part of both my front calipers have gone all corroded. There's no actual problem with the braking as such, but the cars only done just over 20k miles.

Is this me being a fussy bugger or is this something I should take up with Audi? Cars a late 09 A8L so obviously still well in the 3 year warranty period, even though I bought it from an indy dealer.

Here's a couple of crap pics but you get the idea: