I would call focal NA at 888-340-4403 to verify any dealer. Focal NA doesn't seem to publish a list of authorized dealers, other than for car stereo.
http://focal-america.com/support doesn't list headphones.com as authorized.
That said, I'm not sure Focal America even knows Focal makes and sells headphones (or home speakers, for that matter)! Their website is all about car stereos.
ahh, I just went to focal.com rather than focal-america.com.
They list authorized dealers and you can specify what you want to buy, like Headphones. They don't have a way to put in a dealer name. They can only search by location. Not good.
https://store.focal.com/en/store-locator#!country=US
A whois search of headphones.com shows the domain is owned by headsets.com. Interesting. Headsets.com is based in San Francisco. Neither they, nor headphones.com are listed as authorized dealers for Focal. The fact that headphones.com doesn't list an address or location on their web site would normally make me very squeamish about them. Scamadvisor.com shows headphones.com as 100% safe.
Now Jason says Headphones.com is legit, so I would take that as very positive. Still, Focal needs to keep its on-line database up to date.