If its like the aircraft if fly now, or the Seminole i did the IR initial on, the horn will sound when the gear is up and one or both power levers are at or within a few degrees of flight idle. There is usually a horn cancel button to silence this, in the case of, say, a rapid descent.
Perhaps the Examiner pressed this?
IIRC on the seminole, the horn couldnt be cancelled with landing flaps down and gear up, but could with intermediate flap.
On a lighter note, as most of the descents i do now are at flight idle, it prompts many calls (as the horn starts blaring) "don't worry, i've got the horn..."
