Nice "copper" pipes they have there.
I think that the only defect is the fact that the "paint" flaked off. Don't worry about it.
Although copper is an excellent conductor of heat, it easily oxidizes, and can deform under sustained mechanical forces.
In the case of a heat pipe, it isn't the tubing, but the fluid inside that makes all the difference.
I would worry about the flickering or any other artifacts. That could indicate damage. How are the GPU's temperatures under load? As long as they aren't too high, then I would say that the damage is only cosmetic.
My gpu temps are 24 on idle and 60 on load.and the flickering only happens when browsing internet not in games.in the latest drive release,AMD has claimed to eliminate the issue, but its still exist on my card, although much less then before. Sorry for my English