Normal
I would suggest taking a look at the fin spacing arrangement being used in a natural convection heatsink of similar size. Without forced airflow I don't think the air is going to make it through the entire length of the fins. If you use spacing based on natural convection, your fan should improve the heat dissipation but won't be essential to it's operation. What kmpkt said is the most important thing: Fins that are too far away, you lose efficiency, but too close and it won't work at all.
