“I saved that one for you guys,” said Sondre Lerche, premiering a new song last night at the Bowery Ballroom. “I could have played it up in Canada, but did I? No effin’ way!” The 26-year-old Norwegian singer-songwriter’s infectious enthusiasm, and the fact that he was the lone figure onstage for most of the evening, made it feel as if one had been invited into a crush’s bedroom to chat and hear a few tunes. Lerche discussed his record coming out next year, congratulated us on our new president, and professed his love for Polaroids. (The last bit was a sly bit of marketing — the merch table featured his Polaroid Pumpkin Party EP, a six-song homemade CD packaged with casual Polaroid pictures of, well, himself.) He later played an extended bridge so speedily on his guitar that we feared he’d hurt his finger, as he did at Joe’s Pub earlier this year. He didn’t! After that, opener Sylvie Lewis came onstage for some duets, but sensing the fandom in the room, she opted at times to simply remain silent, allowing the audience to fill in the void. And fill the void they did, especially during the sing-along “Two Way Monologue.” But they were probably just thinking, Isn’t he dreamy?