It's probably more a case of opinion - he doesn't seem to think it's weird because it's Leonard. He's got more quirks and hangups than most people, but he still means everything in the world to Mick. He keeps the kiss soft and easy, maybe parting his lips a little but holding back on deepening it for the moment.

God. He could die happy right here and now with Lenny in his arms, finally finally able to kiss him.