In a small bowl, mix the goat cheese and olive oil. Divide the goat cheese mixture between the 4 pizzas, making sure to leave a 3/4-inch rim around the pizza for the crust. Smooth the goat cheese so that the topping is only 1/8- to 1/4-inch thick. Scatter the asparagus over the pizzas and cook the pizzas on the griddle until the dough is done, but not brown, about 3 1/2 minutes. Serve immediately.