I wouldn't have said anything. Yes, he's being a bit inconsiderate, but not all of us are car nuts and it is only a bit of sawdust: Cement dust I'd have been far more annoyed at.
We too have issues with neighbours blocking us in and generally being arses by making noise and stuff, but we let it go as they take parcels for us when we're out and we take their driveway when we have friends with nice cars round. Give and take really, not worth starting a huge argument over it. If you think he's still pi**ed off then take a four-pack round, have a laugh and a joke about it and he'll probably be a bit more thoughtful next time seeing as how you're now his mate.