It's fairly normal I think in the mass produced brands. It's up to you if you are willing to accept it. Take it back and ask for a new one if you think it is unacceptable. I have heard of people doing this with frames with similar marks on them.
Update: Took the bike back in and unfortunately they said nothing can be done about it as it is normal. I had a look around the store with a friend to inspect other bikes on display and couldn't find any similar markings to what my bike has. I still can't buy this as normal since Giant's warranty claim all their bikes are free from defects.
If you are really annoyed by it write to Giant and send them the pictures. They might not be able to do anything but you are telling them that people care about such things, I'm surprised that got through QC. The Defy 1 is a good bike and you can relax and enjoy riding it for many many years. The first time you drop it or have it fall over those small imperfections will be forgotten. Good luck.
It's been great for me up until now and got past worrying about those small nicks, but after test riding a cyclocross bike, it feels much more comfortable for me and like the ride much better than a road bike. I originally came from a cyclocross bike so thought a road bike would be nice for a change.