Annie was going to say that she had missed him, too, but why do that when an enthusiastic agreement could just be hummed into the kiss? Kissing was better than talking (though she loved talking to Diego, even and especially when it was about loving and/or missing one another), and this way she could also wrap her legs loosely up around him to keep him right where he was for now.

Because she'd missed him. And also because she wanted to rub a thumb across one of his nipples and see what he did in response.