by then this was no longer a surprise (that he didn't tell them about wars he intended to conduct, that is, despite AW being his heir presumptative)

Going back in time a couple thousand years, to the wars among Alexander's successors, this reminds me of the time Demetrius wanted his father the king, Antigonus, to tell him when he planned to march, and Antigonus quipped, "Why? Are you afraid you alone of all the army will not hear the trumpet?"