ajax - GET request keeps using same old cookie on each session - ajax

Question

Here is my two ajax requests:
$.ajax({
type: "POST",
contentType: "application/x-www-form-urlencoded ",
url: "https://example.com/j_spring_security_check",
data: { j_username: "mmm#mmmm.com", j_password: "mmmm" },
error: function (request, status, error) {
alert("POST LOG IN REQUEST:\t" + request + "\nSTATUS:\t" + status +
"\nERROR:\t" + error);
}
});
$.ajax({
type: "GET",
dataType: "json",
xhrFields: {
withCredentials: true
},
url: "https://mmm.com/rest/xxx/",
success: function(output, status, xhr) {
var flight = output;
alert(flight[0].flight.toAirport.name);
//return flight;
},
error: function (request, status, error) {
alert("GET ALL FLIGHTS REQUEST:\t" + request + "\nSTATUS:\t" + status +
"\nERROR:\t" + error);
}
});
When I run the code and use firebug - the second request keeps using the same old cookie in every new session. What I want to happen is that the second request will use the cookie from my first POST(login) request. I have tried several variations of withCredentials: true/false and crossDomain: true/false on both requests.
When i clear the cookies, the get request will create it's own cookie. Then I refresh the page to let the script run again. The POST request will create a new cookie(as it should), but the get request will re-use the cookie it made before.