Spontaneous sex change in chicken not a joke?

http://www.bbc.co.uk/news/uk-england-cambridgeshire-12906196

So far as I know, this is not some April Fool joke. The date on the story is 3/31/11.
Basically, a hen became a sort-of rooster, crowing, strutting and changing comb and wattle and quit laying eggs, after a molt. Veternary suggests reason as though it is not unusual.