Yep got this as well, seems that if you remove the checks below it works. This code seems to be the culprit. Not sure why it was added. It stops the updated form values from being submitted by using the old values. I think the current form values should just be sent everytime

                    var expMonthUsed = scope.expMonth ? true : false;
                    var expYearUsed = scope.expYear ? true : false;

                    if (!(expMonthUsed && expYearUsed)) {
                        var exp = Common.parseExpiry(scope.expiry);
                        scope.expMonth = exp.month;
                        scope.expYear = exp.year;
                    }

I also agree with @jamesblackwell , the check there is meaningless and should get the new value every time user submit the form.

It's been a while since I've looked at this, but if I remember correctly, the check needs to be there in situations where the UI has separate fields for scope.expMonth and scope.expYear. Getting the values from scope.expiry only makes sense if scope.expiry is actually being used.

Changing the lines

scope.expiryMonth = expMonthUsed ? scope.expMonth : null;
scope.expiryYear = expYearUsed ? scope.expMonth : null;

to

scope.expMonth = expMonthUsed ? scope.expMonth : null;
scope.expYear = expYearUsed ? scope.expYear : null;

as in #32 fixes the issue for scope.expiry without breaking the use of scope.expMonth and scope.expYear as individual fields.