What are you using for a cap & rotor? OEM or Autozone, etc.? I've never seen an OEM cap do this, but have seen it from cheap-ass caps made in China with Bosch slapped on them.
This is what happened on another one of my Nissans last time I used a non-OEM cap and rotor:
The rotor came apart, and its loctite-installed (blue) retaining bolt flew out and punched holes (plural) in the cap. The amazing part is the car ran like that for awhile - weeks, month or two, not sure. Notice the corrosion, too. It even passed CT emissions, but for the first time it wasn't at the bottom of the limits like usual.
Wow, that thing is really beat to hell! That must be a Hitachi style, looks different than the one on my 95 200sx. I've lately been using a rotor and cap that I bought from Oreilly Auto. Has a lifetime warranty, I've already gotten one replacement in about the last 3 months. Few days ago the cap already had bad deposits on the points with big white flakes that I scraped off with a file. Gas mileage has been pretty poor too, with about 25mpg, 80/20 Hwy/Cty. Not sure what is going on with the rotor and cap. Seems I remember it doing the same with the Factory parts. Maybe I'll give it another shot.