(you can skip the first paragraph if you want to go straight to my question)
my bike came with an FSA gossamer pro BB30 crank/chainrings and a shimano 105 front derailleur. it's had persistent front shifting issues since i bought it, and until now i (and others, including mechanics) have just chalked it up to poor FD adjustment, shifting under load, etc. but i knew there had to be something else going on. when downshifting from big to small ring, the chain would get stuck, come around the back, and slam into the back of the FD. i went through three FDs this way. today, my LBS finally decided i needed new chainrings. they swapped them out (along with the FD, which was bent to heck once again) for new FSA rings and the shifting is now perfect. better than it's ever been going up and down.

so here's my question. i have about 6000 miles on this bike/crank/chainrings, including indoor and outdoor miles. i lube the chain regularly and change it when it's worn. i thought chainrings lasted a long time. are the FSA chainrings just so crappy that they wear out after 6000 miles, or is it likely there was something wrong with them when i bought the bike - especially considering that even then it never shifted as well as i expected it to?