Are you saying he waited until the dodge of minato was triggered or minato's mystery was triggered - there's a difference between the two. Assuming he had the initiative, which is important to explain as you did not, he might want to trigger the dodge as people on auto or noobs that fight against dodge ninjas foolish will use their mystery before triggering the dodge. Of course it doesn't matter if he waited if you had the initiative as madara would charka steal if he did not trigger the mystery.