Have a picture on your phone showing the back of a "for USA only" headstock. "Look Ma, Mine doesn't say that!" I seriously doubt if Customs has any idea how far back PRS started that procedure. I can't imagine that you'd be in any trouble unless you unknowingly stated you were transporting a Brazilian Rosewood instrument or if you had paperwork in the case stating as such (certificate, sales receipt, Brazilian sheet, TRC, etc.). BTW, I fully understand CITES and respect what it is trying to prevent, but the guitar thing got a little carried away, IMO.