Shashika Sudasinghe

Hello, I have some kind of a same problem. Bought a 2013 Express with 4.3 v6. Took it to get the first oil change and it took 6qts instead of 4.5qts. I search everywhere and all of the sites states that 4.3 engine takes 4.5qts. But my mechanic put whole 6qts anyway. I was just wondering why and does it matter when it comes to over filling the engine with recommended amount of oil? can someone please explain.