Some states may require proof of age for a pre-1899 Antique Firearm, but they are not required to be transferred by an FFL under current Federal law. As Geo is saying, there are quite a few FFL holders who don't seem to wish to know the law when it comes to handling Antiques. Since guns built prior to 1899 are not even considered firearms in the legal sense of the word, they are not even supposed to be entered into the FFL's bound ledger book.
https://www.atf.gov/rules-and-regulations/laws-alcohol-tobacco-firearms-and-explosives
