2.0 aluminum series leaking oil from nitrogen port

I had a local shop rebuild my icon 2.5 C/Os and my 2.0 aluminum series rear shocks using icon rebuild kits. After about a week I noticed oil leaking out of the nitrogen fill port on one of them, I took it back too the shop and after about a month without taking it apart to inspect it they said there is nothing they can do. I have never heard of these leaking out of the fill port as I thought it was a self sealing membrane, does anyone know what is going on here?

 

Got ahold of chuck from Icon he sold me the correct part for $6 as it does not come in the rebuild kit, it's an uncommon part. Also told me how it is installed thanks again!