I have heard of dan grades confusing a low ranked kyu grade in hakama for a dan grade and therefore going fell for leather with them when the uke couldnt cope.
But then again Ive trained with visiting dan grades from other organisations who didnt ask my kyu rank and just proceeded to batter me senseless anyway, so I guess its all immaterial.
In any case it seems strange to me to train for several years without hakama, get to shodan and then have to learn how to take ukemi, walk around and do technique without tripping or injuring yourself. Maybe its an initiation joke? "Hes a black belt now, he thinks hes great. Lets make him wear this stupid skirt!".