Is it normal to like to cut my wife's nails while she sleeps?

You have issues. I mean why aren't you asleep instead of staying awake just so you could cutt your wife's nail.

This is the only time this is normal.

It crap my pants if I slept in the same room as you.

Is this a question that needs to be asked ? Of coarse it's normal, everybody does it.

How does she not notice...or do you file them down, as well?

Cutting a womans nails in her sleep could have some bad results. Cutting them at all could have some bad results unless you're good at it. Dose she have rediculously long nails? If so, Normal.