Lota of angles that this could still be an open case, IMO. What if Gibson ordered 6mm wood and it came in as 10mm? All it takes is a goof anywhere in the chain. Wrong part #, guy just didn't pass it thru the planer a couple more times and sent it out, nobody ever checked the actual thickness (or did knowingly and marked it wrong), an order comes thru to billing, they call the guy that orders and he says 'yep, theres an order of that expected' from his golf cart ... until gubmint showed up with a micrometer and gave it a good measuring.
I wouldn't doubt they knew it came in a little heavy, but since it was marked (and marketed)as legal size they just went with it; cost less, gives a little better choice of wood to guys here to work with. I don't think Gibson should be responsible for dimensions taken on products thousands of miles away. Should they have gone to the feds and said "we ordered 6mm wood and they sent 10mm, now we have to plane it more"?

Now if it came through labeled as 10mm, then why was it allowed to go through? I would think that something I sent through customs properly labeled would be good to go. They should know the law there in that office better than me.
4mm is kinda a small amount to be fighting over. It's another run thru the planer, done here or there. Not a lot of environmental impact there deciding where it gets done. Seems silly to me, even though I know the law says it's so. Intent of law vs letter of law I guess.

Make your sound your own!
.. I do not work here, but the benefits are still awesome