I'm not too sure which the last series is, as I was only introduced fairly shortly before his death to Bourdain's work, but as someone new to him — all his appearances have that faint background noise of world weary despair. It's not overwrought and doesn't in any way taint his shows, but it's a distinct undercurrent. Perhaps I'm sensitive to his language and vaguely grim manner because I've in a very small way seen into various worlds of despair, but I was in no way surprised by his last choice.
It's sad, but he seemed to have lived a good life and at least was in control of his final journey — most of us aren't.