well, my left hinge cracked on my ds lite. this is my replacement unit, that is about a month and a half old (got it because my original had a non-clicky R button)
i also have really hard to see hairline fractures on the body above the R button.
nintendo said they would fix the hinge crack, but probably not the hairline cracks. they said those are caused by stress and probably dropping the unit. it would cost me about $50 to fix those. i told them i keep the ds in an official nintendo ds case and i have never abused it. i also told them to forget it about the hairline cracks, because even if they spread, it doesn't look like they would do any damage.
then i asked if this is a common problem. they guy said he gets about one of these calls a day and they aren't sure why the plastic is cracking there, that they are working on a fix for it. i also asked if this happens with the pink or blue or black units and he says he's never seen one yet. but his reasoning was that there are alot less of those units and that cracks are harder to see. i asked if the plastics were improved on those models, but he couldn't confirm that.
then i asked if my replacement, if i even got one, would have the chance of a dead pixel, if i could return it. he said a single pixel is normal and industry standard, but nintendo cares, so they would replace it. he also made notes in my file that i was a second time warranty return and to check out the unit for dead pixels if sending out a new unit.
so, all in all, nintendo customer service is great. i'm waiting for my rma label, then it should be about a week till they either fix my problem or replace my unit.