I do not think so as we have 4 samples at livedemo and more at dev demo which working fine. Show your page. Make sure you no reRendering the autocomplete component itself for example from the request which shows the popup(using ajax rendered outputPanel around for example).
B.t.w. please also check using 4.0.1 snapshot and not only 4.0.0.. there were some issues in scrollable areas not sure where was fixed(but remember that fixed )