I often use oil on top of the crust--to prevent migration of water from the sauce into the dough, for added flavor, or to improve browning of the rim of the crust. Occasionally I will also use a high quality olive oil on the pizza after baking. For some this is a no no, but I happen to like the fresh flavor of a good raw olive oil, even a strong tasting one.
However, I am having a tough time figuring out the physics and thermodynamics of your situation where you have placed the olive oil on top of the cheese. I could understand what happened if you had put olive oil in the dough to get a softer, more tender crumb (but for even that to happen you would have needed a lot of olive oil, around 7% by weight of flour).
The laws of thermodynamics say that heat will transfer in a direction from a hot object to a cooler object. I suspect that olive oil has a higher heat capacity (that is, it heats up faster and retains its heat longer) than sauce or cheese. If that is so, then it would seem to follow that the transfer of heat from the oil would be largely into the air which, as an insulator, has a lower heat capacity than the toppings on the pizza. Otherwise the cheese could overcook and start to turn brown faster than if no olive oil were used. It's possible in your case that the pizza looked done sooner than usual because of the high heat transfer characteristics of the olive oil and the color of the crust and possibly the cheese. You didn't indicate how long the pizza was baked in relation to the other pizzas, but if the pizza with the olive oil on the cheese baked faster, for whatever principles of thermodynamics applied in your case, then there would be less drying of the crust and more moisture retention, leading to a softer and more tender crumb. I'm no expert on pizza/oven thermodynamics, so I am receptive to a more informed analysis from others who have a better grasp of the physics involved here.