What is peculiar to pearl about the minister? the scarlet letter

Pearl finds the ministers behavior in public and private quite contradictory. She sees him as sad.

"In the dark night-time, he calls us to him, and holds thy hand and mine, as when we stood with him on the scaffold yonder! And in the deep forest, where only the old trees can hear, and the strip of sky see it, he talks with thee, sitting on a heap of moss! And he kisses my forehead, too, so that the little brook would hardly wash it off! But here in the sunny day, and among all the people, he knows us not; nor must we know him! A strange, sad man is he, with his hand always over his heart!”