I wouldn't worry about it yet - especially if your energy is good. It is very common with primal eating to have your appetite "cycle". Some weeks I have no appetite at all - then all of a sudden I'm eating everything in sight - then I'm back to no appetite. It all seems to work out in the end.
If it continues long term you can try adding more fats to your food to bump the calories, making sure you have plenty of zinc in your diet, or adding in more primal carbohydrates to stimulate your appetite.