Tom/Barb: Yes, I was coming up from behind i.e. "passing or overtaking" the other coach. I was not going in the opposite direction or "meeting" the other coach.
SideHillSoup: I have been very impressed during this entire trip at how courteous other drivers have been by observing the "5 car rule." By and large, with rock haulers being the exception, almost everyone has also slowed down to match my speed when meeting each other on gravel sections too, hence no chips in 3 round trips on the Alaskan Highway. This incident happened on Highway 2 between Dawson City and the Highway 1 junction to Whitehorse on a very flat section of the paved road with at least a mile visibility. Which, by the way, is one of the better roads we have been on all summer! The problem happened as I was moving into the left lane to complete my pass the other coach drifted or eased the right side wheels off the road. This was not intentional it just happened. Yes, Tom/Barb I know this was what happened because he was in the same RV park as us later that evening and we had a conversation. They were very apologetic about causing the damage and stated they didn't pull off the road intentionally. As previously stated he was off the pavement and on the shoulder for less than 5 seconds.
As gbopp states: "It's more important to be safe." I would have followed him to Whitehorse if he had not turned on his blinker and started slowing down. Again I say, KEEP IT ON THE ROAD!