title: Persistent AuthCookie is set but being redirected to login
body: <p>I'm having problems with using a persistent AuthCookie. The validation and login works perfectly and if i close the browser and re-open it the authentication is still valid no redirect to the login page is done.
  I'm not sure what the exact time is but let's say that if close the browser without logging off and only reopen it 20 minutes later I'll be redirected to the login page even though the cookie is set when I check with web developer tools and it's expiration date is one month from now.</p>
  
  <p>All i'm doing after validating the users credentials is</p>
  
  <pre><code>FormsAuthentication.SetAuthCookie(model.UserName, model.RememberMe);
  </code></pre>
  
  <p>And in my Web.Config I have it set like</p>
  
  <pre><code>&lt;configuration&gt;
      &lt;system.web&gt;
      ...
      &lt;authentication mode="Forms"&gt;
          &lt;forms cookieless="UseCookies" loginUrl="~/Utilizador/Login" name="SMOAuth" slidingExpiration="true" timeout="43829"/&gt;
      &lt;/authentication&gt;
      ...
  </code></pre>
  
  <p>Also tried to hard-code the machine key as suggested <a href="https://stackoverflow.com/questions/1663991/asp-net-mvc-formsauthentication-cookie-timeout-cannot-be-increased?rq=1#3755755">here</a> and a few other places, but to no effect</p>
  
  <pre><code>&lt;machineKey validationKey="Validation_Key_Here" decryptionKey="Decrypt_Key_Here" validation="SHA1" decryption="AES"/&gt;
  </code></pre>
  
  <p>I'm having a hard time trying to figure this out</p>