I’m glad you were mostly ok. It didn’t seem like there was wind, but could have been turbulence from the truck passing the truck.
Besides the one guy here who brags about his MPG and “slipstreaming” trucks, I think the rest of us don’t like to follow trucks close.
As you found, they can stir up a a lot of debris in a hurry, but can happen even if they don’t go off the road. Of course, you also can’t see what is going on in front of you which gives you much less time to react if needed. If you can’t see in front of them, I’d say you are too close.