It wasn't clear to Carol that she was nervous until Daryl responds and she feels her tension draining away. Staying as they were would be fine and so would more of this, but what would not be fine is anything one-sided. She's precariously enough balanced as it is.

The part of her that's supposed to tell her this is a bad idea never pipes up so she returns the kiss with lazy contentment. It's the wrong time but there's not going to be a right one, she's mourning and so is he but that's just as much a part of their lives as breathing. She's not sure of herself but he's sure of her.

In so many ways, the ways that matter, nothing has changed. This is only going to be difficult if she makes it that way. After so much ambiguity and doubt, this choice is easy. She's not only not running away, she's running towards someone; only he could bring that out, and maybe only since she came here. This is as close a clean slate as she'll get, it doesn't heal all the damage by a longshot but it's amazing how much one or two less cracks make things feel so solid.

Even if the arm she's laying on his falling asleep and when she tries to shift off it she kicks him in the shin, and even if that makes her giggle against his mouth, somehow that only makes it better.