I have a registration form that is validated via jQuery Validate and while
the form catches errors properly and displays the validation error message,
it doesn't use my "label label-important" class until I force the
validation/click the submit button* a second time*.

Test it here: http://jsbin.com/uguwem/12/

Here's my js code:

$('#registrationform').validate({
    highlight: function (element, errorClass, validClass) {
        $(element).parents("div[class='control-group']").addClass("error");
        $(element.form).find("span[for=" + element.id + "]").addClass("label label-important");
        },
        unhighlight: function (element, errorClass, validClass) {
                $(element).parents(".error").removeClass("error");
        },
        errorElement: 'span'
 });