Funny, but as newbie mamas and papas we get so wrapped up in feeding, entertaining, toxins, behavior, do's and don'ts that the little things like anatomy slide right by! Ha.
Timber is like that too. I spray him all the time, but a couple of times a month, usually after I spray him, he will go stick his head in his water bowl. That is my signal to get the dish and he dives right in.
So glad to hear that Gilbert weathered the trip so well I can't get over how much progress Gilbert has made in the last few months. Moral of the story... never give up