zombie84 said:

Usually, but I think the reason is that the pinky is used less in everyday life so the longer nail doesn't interfere with things as much and is less conspicuous. But the index would probably be easier for the um, intended usage. And also for women, some women have every nail that long, so it's not a big deal.

I guess this does explain Carrie's slightly worn-out appearance in the film in very direct ways.

Maybe she used the index nail to throw off suspicions. But it's quite clear the other nails are cut.

I imagine this will find its way back to George and be added to the list of revisions for the next iteration of the original vision of Star Wars.