Embedded Glassfish "randomly" responds to requests after restart and redeploy

Question

We use embedded glassfish version 3.2-b06 for integration tests.

The problem is that sometimes test that call our web service (RESTful) returns a 404 response and sometimes 200.

For example:

@Test
public void test() throws Exception {
    int code = sendPOST(URL);
    Assert.assertEquals(200, code);
}

But if I add Thread.sleep (1000) at the beginning of the test - everything is fine always.

@Test
public void test() throws Exception {
    Thread.sleep(1000);
    int code = sendPOST(URL);
    Assert.assertEquals(200, code);
}

We are deploying the application as follows:

@BeforeClass
public void init() {    
    GlassFishProperties glassFishProperties = new GlassFishProperties();      
    glassfish = GlassFishRuntime.bootstrap().newGlassFish(glassFishProperties);
    glassfish.start();
    File ear = new File("target/ear.ear");      
    Deployer deployer = glassfish.getDeployer();
    deployer.deploy(ear);
    context = new InitialContext();
}

From logs it's clear that ear is deployed.

What could be wrong?

EDIT #1

It turned out that when the code changes the tests pass. But when I run repeated tests, they fail.