it can mess with the flavour iirc. i just do it for convenience because i like a nice cold bar of chocolate but i, chocolate expert extraordinaire, am able to taste the difference in the chocolate when stored inside a fridge. ideally u wanna store it completely wrapped (or covered with alternate OBJECTS such as paper towels) in a cupboard unless ur room temperature is like 30°C or something in which case it would maybe be reasonable to store in a fridge