I saw something tonight as well. Trump is always confident, but tonight when he said he was the presumptive nominee, there was an aura surrounding him of total and complete assurance. Very interesting.
Of course! He's proved it - he's winning. It's not just braggadocio, now it is results.
Manafort said this sort of transformation (not so much in Trump, but it will show up there too) from "running" to "presumptive nominee" was inevitable, and would be complete by the middle of May.