That is where it hooks up, and it isn't so bad once you remove that side of the GC. You just have to take the two screws out of the bottom(if no autosampler is on it) and slide it to the rear if I recall correctly. Just tighten with a 7/16" open end wrench, I have done it quite a few times. If you want to make it easier if you plan to move the instrument again, just cut a piece of copper tubing to reach out the back of the GC then put a union on it there, so next time you can just attach the gas lines right at the rear of the instrument.
Just be glad you are not having to hook up two carrier gas lines, two fuel gas lines, two air lines and two makeup gas lines all inside there, it can get to be a mess.