Jamie didn't mean anything by it - he tends to tease his friends from time to time. Especially the girls. It's actually a sign that he does like you. But it's also true he probably wouldn't have dared try if anyone else from Serenity was there - even Inara. He knows that people tend to take that sort of thing the wrong way.

He reaches out a hand to stop Kaylee before she can completely leave. "Och, no, it's fine. I just wasna expecting it to be the cactus juice." Which, to be honest, is pretty good. "Honestly, I'd rather ye not bother on my account."