Cedar grows in wet ground well. One thing that it has to adapt to this environment and fight the bacteria that would rot it out while still young is that it has it's own aromatic oils and some toxic compounds. cedars that grow in jungle areas of the world have more of these than those that grow in colder, drier places. These are the toxins that keep cedar fence posts from rotting and that make a closet smell nice while repelling moths.
If you didn't have a reaction to the dust while actually doing the sanding, you have little to worry about. Most woodworkers who create cedar dust learn eventually that it is good to wear a dust mask.
I have quit using Port Orford cedaar very much because it has irritated the sinuses of my crew members and it landed me in the hospital with a lung irritation that gave me symptoms like a heart attack, great pain with every atempt to breathe in.