Severus tried to push anything and everything related to Harry or anyone at Hogwarts out of his mind. This was all about Lily, he could worry about the rest later, hopefully a lot later.
He leaned in and kissed Lily, a little more sure of himself this time because he knew Lily wanted him to kiss her. He kept one of his hands on Lily's, the other he moved to her upper arm, not really sure what to do with his hands. He wanted to enjoy this but he also wanted to make it perfect for her, he didn't want to do anything that would make Lily uncomfortable.