I have been searching for why they would consider Ebony as a reason to bother someone about a guitar. It IS scarce and valuable, but not quite 'endandered' yet. I don't find info that CITES is prohibiting it.

There is also MUCH confusion about the differences and nomenclature between Ebony (often called African Blackwood(a Dalbergia) and "Gabon Ebony" (Diospyros spp.). African Blackwood is the usual wood for musical instruments, and this site confuses them. One of the confusions is that Diospyros dendo often called "Gaboon Ebony"...which itself is not quite correct, as "Gabon Ebony" is the actual standard trade name.

this page by a knife maker gets them backward
   African Blackwood is a less stable, harder to work wood...though it is used for expensive carvings in Kenya & Tanzania. (see 'Makonde')

this site, about Blackwood helps clarify things, as does this site to explain naming (Gabon is a country..Gaboon is a snake)

...........Now..with all that confusion, how can anyone expect a customs agent to tell what a guitar fingerboard or bridge is made of?

I sometimes use small pieces of Ebony for inlay and handles for turned box tops, and I would MUCH rather use really dense Blackwood, as Ebony can crack..even months later.