LOL! Same thing happened to my dobe Kyuss. It took forever to train him to walk through my pass through gate!The only problem I have .. and its more of a good problem, is if one of my girls knocks down a baby gate, they still will not cross the threshold of whatever doorway it was blocking, they both have had the gate fall ON them and therefore are afraid of it ..
I would attempt retraining. Maybe jimmy the door up as Adara suggested.