Interviewers are always surprised by how well Daniel and Tom get on. For some reason that Tom doesn't quite get, they never seem to understand that the boys aren't Harry and Draco, and don't have such a hateful relationship as their characters do.
Quite the opposite, in fact. They were more or less forced to become friends, on set: Dan has more scenes alone with Tom than he does with even Rupert or Emma, since the Trio are very rarely seen as only two. And although those two are his friends, he and Tom are closer.
So when Dan came to Tom and shyly asked him for help practising kissing, Tom agreed without hesitation.