I've never heard of granite being stickier than marble for any kind of food. The only thing I can think of that the person might have experienced is an increase in surface tension due to granite's lower porosity. Even that is somewhat relative anyway, since untreated marble will absorb more water at its surface in higher humidity environments, and then you deal specifically with interface tension. If both are treated, which is likely the case if the person is talking about granite and marble countertops, they should both be exactly the same with respect to "stickiness." The thermal conductivity of granite and marble are relatively the same, with the marble tending to conduct a little less in some cases. That means that in extreme cases, granite will be slightly colder than marble, which would actually make it less "sticky."