Yeah the place that did the plugs and molds were somewhere in Indiana. We were never told the name but there where air pockets everywhere and they are very much overworked. But they were cheaper and that's all the company we make the bodies for was looking at. Costs them more in the end for repairs and work to fix the parts. Some of our molds are over 15 yrs old and just getting to the point of a pinholes stRting.  So to avoid it really it comes down to good plug preparation and mold making due to company recommendations. 

Moulds should not usually have any porosity but can do if they have been worked on and sanded through into what may be a poorly laminated material behind the gel coat.

New moulds done right should be right.

You could also refinish the mould you have by spraying the whole surface with new gel material, then sanding and polishing to get great new finish. Duratec has resin products and advice specifically for doing this.

http://duratec1.com/duratec/?p=811#more-811

Okay im sure this has been brought up but I couldnt find it with searching. These arent molds we made but ours do do this, but a lot less and since im new to mold making I thought I would ask.