Ah cool! I knew about the roaming resort characters but not their dedicated bus! Im pretty sure those character resort pop ups are unannounced by design to keep crowds down.
And word would get out and they would draw crowds. This really is a case where because of the internet we can't know where nice things are going to be.
Pluto and Goofy were at the Poly one time that I saw in February. Looked like they were heading to an incognito bus though. No big “OMG LOOK AT THIS” wrapped thing. Very much on the downlow.