http ajax request fails randomly

I'm not sure it this is a bug or something on our web server (Apache 2.2.1) but randomly the first ajax request sent to our web server will not have a SSL_SESSION_ID.  I've printed out and compared the environment variables and there are only two that differ from a working and non working request, but I'm not sure what to make of them.

For a working connection they show up as:

HTTP_ORIGIN: https://ourservername.com

HTTP_X_REQUESTED_WITH: XMLHttpRequest

For a failed attempt they show up as:

HTTP_ORIGIN: file://

HTTP_X_REQUESTED_WITH: com.ourservername.mmb (mmb is the folder our app resides in)

If you wait 10 seconds and try the request a second time, it works fine, and for that session all further requests also work.  It's just the very first ones (if you wait less than about 10 seconds, it may or may not continue to fail).

It's a pretty standard request using a datasource:

    app.appTokenData = new kendo.data.DataSource({
        transport: {
            read: {
                url: "https://ourservername.com/cgi-bin/mmb/login.cgi",
                dataType: "json",
                type: "post",
                data: {
                    username: function () {
                        return $('#username').val();
                    },
                    password: function () {
                        return $('#password').val();
                    },
                    datacentre: function () {
                        return $('#datacentre').val();
                    }
                }
            }
        },
 ...

Has anyone had this problem, and what might correct it?