Not really, but son does have the amazing habit of falling into a deep sleep when riding some form a transportation, be it a car, train -can't remember much of the plane trips I've taken with him
And I half seriously wonder if his Japanese part of him has something to do with this. One thing I came away with from the many years I lived in Japan was the apparent ease in which a good number of Japanese quickly fall asleep once they've boarded and sat down, on a bus, train, subway and amazingly (with the exception of drunks) how they would also rouse themselves out of their slumber when the mode of transportation reached the point where they were to get off.
But anyway, on the way back yesterday from his paintballing referee gig, I quickly snapped this one of son. At least he wasn't drooling from the corner of his mouth.