The vettes do it too and they call it "parade clunk" or something like that. Most aftermarket clutches get rid of it but not all of them. I was going through a bunch of vette and ctsv forums reading up on clutches since most companies were selling comparable units to that market for years before the camaro came out. A bit more history on what works and what makes noises or fails if you're interested in looking at a replacement. I'd rather hear from someone whos owned a clutch for years and see how it holds up, the camaro is too new of a platform to get a lot of feedback on longevity.
Mine clunks now and then too but as long as its shifting fine and nothing grinds I don't worry about it. Eventually it'll get replaced with something beefier that hopefully has good manners.