Neil teases a little, because he can't help it. "Aren't we having a drink? We've still got a bit of wine left."

The note of self-consciousness warms Neil through, because he knows that feeling too well. There's a part of him that wants to be forward, bold--they've made the jokes, they've been flirting; it seems natural to see if there's an invitation in there, or just the gentle teasing.