Yes, it is Bones. With all these DC centered forensics shows, and knowing how small a specialized professional community can be, you know all these folks know each other. you can't convince me that Ducky doesn't make it a point to attend every conference session he can presented by the alluring Dr. Scully. And I can so see Brennan and Scully trading eyerolling stories about their encounters with Ducky.

And not that I think every military sniper knows every other military sniper, but in the tv/fanfic world of possibilities I think it's likely that Gibbs and Booth know each other and have perhaps worked or trained together somewhere along the way.