An N4 is high-end enough that I'd demand
some sort of paper trail!!
You're talking, what, $1,000+? Unless it's got a verifiable
COA or the extension number so I can call the Custom Shop (or Boogie Street or Funky Munky or Stephen Davies) directly, then at the very least I'd call it "shady." Where's the receipt from when HE bought it? ...or did it just "fall off the truck"?
Barring verifiable proof, you & the seller should meet up at a quality guitar shop, & be prepared to pay a few $$ to get a pro opinion on actual value. If you offer to pay the tab, & the seller still refuses to go, then I'd guess the guitar's either counterfeit or stolen.
You could maybe even try to bribe the man himself
to get some verification -- you, of course, have already looked up Stephen Davies' guitar shop
Stephen's Stringed Instruments
1733 Westlake Ave. N
Seattle, WA 98109