I'm not sure if this is always the case, maybe for concierge guests in cabanas, they are always hosted by the ship concierge. We had a cabana, were not in concierge and we had someone from Guest Services as our host. We weren't going to tip her anyway (whole different story; had many other issues with her regarding the cabana prior to Castaway Cay) but my feeling was that GS is not a tipped position so they would not be able to accept a tip for cabana hosting.
Which sailing? Your ticker says 1 month. We canceled an adult cabana on the Nov 15th Dream sailing when we had to change plans. I know someone was probably as happy as I was sad.