Bruce had to plaster that gentle smile on his face, as always, his doors to his manor open to a bunch of the elite Gothamites, some even unsavory characters as he well knew, even if others didn't, but he had to keep this facade, to keep the secret he is Batman under wraps, and to keep up appearances of course, he was Bruce Wayne. So this meant fake smiling, gentle jokes, laughing even if he wasn't happy, that's what this was. That's what he did, especially at charity Galas. He had to. And of course, Oswald Cobblepot and others would be there, everyone showed face for Waynes. Strange.
Bruce had just finished speaking with some elite being polite and charismatic as he always was, he had backed up to go get more champagne and to make his important rounds before someone bumped hard into his back and he paused and turned around.