It seems like the .one function is broken. It executes multiple times. I've put some example code on JSFiddle: http://jsfiddle.net/KeesCBakker/8KY9d/5/.

Html:

<button>Create</button>

<div>

</div>

jQuery document load:

$('button').click(function(){

$('div').append('<span>Header1</span>');

$('div').append('<span>Header2</span>');

$('div').trigger('load');

});

$('div').one('load', function(){

$('span').addClass('header');

});

Result:

It keeps adding red header elements, but it should only do so the first time.

Remarks:

When I use 1.5.2 everything works fine.