As far as I remember I have placed the two eldest, those of my dynasty, as his wards myself. I am unsure with the bastard, if I have given him as his ward. He however, the bastard, I have changed his dynastyname at some time, which was a generic bastard dynasty to something different, and edited his COA. That might be the only "odd" thing I can come to think of.
Otherwise this guy have been my steward for many many years, and have been working in my capital the whole time.