It wasn't so much the fact of smiling as the tone and the way she did it--sort of mesmerized. That is radical, radical trust she has going on there, and that level of trust can be dangerous--it can blind a person to problems.

I do think it's essentially redeemed by the fact that all signs say the Doctor has never/will never fail her in that particular trust. But I think it's also fair to find it a little concerning.

I would even go as far as saying it's a form of foreplay. Of course she's nuts/crazy but that's why The Doctor is mad for her.
This I will agree with. Don't get me wrong--I love the jumping off of things trope. I think it's wildly romantic. But sometimes I do have to wonder.