Making a POST request with Angular

Caveat: I am a front-end developer, I don't have much experience with servers.

I'm building an app with Angular 1.2 that pings an API on a different subdomain. The backend dev on the project is using nginx and has set it up to allow cross-domain requests by essentially forwarding the subdomain, or something similar, I believe. I can do an $http.get request just fine, but when I try $http.post I get the Access-Control-Allow-Origin error.

Here's the kicker: I can make the same request with jQuery's $.ajax and it works just fine.

$.ajax({
    type: 'POST',
    url: 'http://api.mydomain.com/v1/customer/',
    data: theData,
    contentType: 'application/x-www-form-urlencoded',
    //contentType: 'text/plain',
    //crossDomain: true,
    success: function(){
        console.log("sent data via jquery");
    }
});

Here's how I have Angular set up:

var myServices = angular.module("myServices", []);

myServices.config(function($httpProvider) {
    $httpProvider.defaults.headers.post['Content-Type'] = 'application/x-www-form-urlencoded';
});

And:

    save: function(payload){
        console.dir($http);
        return $http.post('http://api.mydomain.com/v1/customer/', payload).then(function(result){
            return result;
        });
    },

What am I missing?