Spread one side of each bread slice with the pesto. Top the pesto with a layer of goat cheese. Divide and top 4 slices of the bread with the tomatoes; season with salt and pepper. Set on, goat cheese side down, the other 4 slices of bread. Heat the olive oil in a large non-stick skillet over medium heat. Add the sandwiches and cook 2 to 3 minutes per side, or until golden on the outside and warm in the middle. Cut each sandwich in 2 and serve.