Can Cavalary benefit from the hidden rule?

We ran a scenario recently that required the defender to set up three infantry units in an area, these units were considered hidden. The defender had a Polish Cavalry Platoon and the question was whether the Cavalry squads would have to dismount to get the benefit for hidden. We could find nothing in the rule book stating that Cavalry could not benefit from hidden set up, only references to scouts in a few theatre books that allow scouts to be set up like sniper/observers except if they are mounted.