Hannah didn't think, really; she just followed. Gabriel would be okay while she was gone, since she'd splurged a little and gotten him one of those automatic food-and-water dispenser things that she'd seen at the pet store. Other than that, really, she had no one to get back to; no real commitments to concern herself with.
She went because she wanted to keep an eye on Boyd, to make sure she was okay; but she also went because a part of her didn't want to be alone. It was nice to have someone else there, she thought, climbing into the cab the other had waved down. Even just temporarily.