Is this normal? I noticed that sometimes it can get really wet and I can even see the yellow liquid on my paper. However, sometimes it isn't wet at all and I can re-use my paper 2-3 times. What could be the cause of this?
Some recipes will normally leach the fat in the recipe. Some recipes just do it some of the time, other recipes are notorious for doing it all the time. Generally, it's nothing you have done wrong, fats just do that sometimes.
Jolenealaska is correct when we are talking about the difference between recipes. If it happens when you are using the same recipe, it is a sign of a temperature difference. In general, the same recipe will leach more fat if baked more slowly. So if you have a recipe which generally doesn't leach much, but one time it did leach, your oven was probably set too low, or not had not yet reached the preheat setting.