That is hilarious, dirt bike peeps are so courteous.
Reminds me of one of these 24 hr races I was trundling along minding my own business in the middle of a beautiful day just loving life zipping across a wide field. I heard a big 4 stroke gaining on me so I held my line and was thinking there is tons of room, multiple lines, this guy will blow by me before I ever see him.
Just as he gets near me, a little closer then I would have liked given all the room we had, I hear this very loud yell from the passing rider and then he's gone. It sounded like an angry, get the hell out of the way yell. I was shocked and wondering what the hell all at the same time. What a dick! I remember thinking. Two seconds later I decided to forget about it and get back to my "wow I am such an awesome person to be doing this race, look at me go mode".
Got back to the pits all proud of myself for riding a dirt bike, sometime after a super fast friend stops by, he asks me if I heard him yell to me when he passed me. Turns out it was my buddy yelling encouragement to me as he went by "Hey, go Ed!" or something like that. Oh my god, I was dying, told him my side of the story, we both got a good laugh out of it.