It's most likely off due to the positioning (or more accurately, mis-positioning) of the faux gas cap. I'm sure this part is subject to some positional tolerances making it off from it true ideal location which is causing the panel misalignment.

Pics?

 

1MM of extra space? Hmmm..still within government specs...so, I say you are good to go...

 

Yep, the faux cap is the problem with the install being partially off.
Its rarely centered as the alignment pins dont fit the alignment holes
in the panel tight. The holes are sloppy allowing for a slight
mis-alignment of the faux cap from the factory.

I did a honeycomb first but didnt like it cus of the fit and quality.
I went with the CDC ribbed panel for a more distinctive look.

I also used 3m 4298 adhesion promoter...

 

That's an interesting suggestion I hadn't considered.

I'll try and snap a couple pics before we head out for my niece's recital. I should be able to get them posted late tonight or tomorrow sometime. I was waiting until I got the tail light bezels on, but it wouldn't be bad to have a few comparison pics for down the road.

 

My SHR panel is in transit right now to me. I have gloss black vinyl in the rear right now, but like the look of the panel better. When you first apply it using the adhesion promoter are you able to move it around a bit to get in the right position?

 

NO. That is one thing I'd advise you to be careful with. Once it's down... it's pretty much down for good. We tried fitting it before removing the adhesive covering to see how we were going to position it. Then we removed it to make it stick. The instructions say to flex the panel so that you can put the center against the trunk first and work your way outward. The panel is very sturdy and hard to flex, so this is nearly impossible unless you're The Hulk. As such, we got it down, weren't totally satisfied with the placement, so we were able to pry off the right side. The left side practically wouldn't budge, though. So be very very careful and make sure you have it how you want it before you press down because you probably will not get a second chance.