At the coin show today I found a couple slabbed nickels. The slabber was INB, a company which I steer clear of because of notoriously bad grading and service. Some of the nickels I looked at had golden toning. I wouldn't think this new of coin would have toning, or was it "helped"? I didn't buy them anyway, they were overpriced.
No way to "prove" it, but I would be suspicious of such a proof. Most proofs do not leave the package, making such toning questionable at best. If it were a business strike, there could be more doubt but I still wouldn't like the coin.
Impossible to say if it's AT. The point is actually moot for this though. Gold toning is not really a desirable toning for toned collectors. Gold toning is very common naturally and also easy to achieve artificially. So it generally won't bring any sort of premium. It occurs due to warmer storage temperatures. On that note, go stick some lustrous nickels on your dashboard in your car during the summer. You will have gold toned nickels soon enough.