I can't speak to code violations, but this is a bad idea. If the valve leaks, it will leak right on the electrical box. Move the box out of the shower's wall.

Good practice perhaps would be to put the outlet in the adjacent stud bay.

But it probably isn't a code violation, so if you want it moved then you'll pay for it.

You could also just put some blocking above the outlet to prevent any drips from hitting the box directly (in the off chance that your plumbing fails). More for peace of mind than anything else.

That said, if I was doing it I wouldn't have put the box there in the first place. But it isn't a big deal that it's there.

I agree with Kudzu. If you get water in there, you've got more problems than just the electrical ones. Make sure they use a proper technique when finishing the shower wall. CEMENT BOARD IS NOT WATERPROOF. I about took the head off the tile guys who started tiling over cement board that had neither a vaporbarrier behind it or the waterproof membrane painted on the front.

Nonissue.