So, I just finished two 4 cuft HST18 builds. I mounted the sub and pushed it in a bit to verify that the box is sealed. After being pushed the sub snaps back into place, no slow movement or anything, but I hear a force of air coming out of the unused connections of the 4 pole neutrik, no where else. When I plug in a speakon cable, it's significantly diminished, but I can detect a small amount of air coming out of it still. Is this normal? If not, how should I alleviate the issue?