My S5 is in the factory right now for exactly this reason - microblisters on various parts of the car usually at the edges of the paintwork i.e. around the rear lights/rear arches etc. I've not yet had a report from the factory as to why this has occurred and once resprayed I will be expected them to offer a new warranty on the paintwork to guard against the same happening in the future.
My local dealer also told me that they had another S5 going back to remedy the same thing so these seemingly aren't isolated cases!
Yeah, blistering around edges/wheel arches of rear wings, the side vents to the front wings and along their bottom edge and also between the front wings/valance.
Can I ask if you know whether they are re-spraying the car in its entirety or just the parts where the blistering has manifested itself?
I've just today asked the question of Morgan, via my dealer, what guarantee they can provide re-bits of painted body that can't be seen or where the issue hasn't (yet?) manifested itself and also in relation to the newly sprayed parts particularly given my original manufacturer's warranty will expire next spring.