I've noticed something strange when driving.

When the windows are closed and I pull the window switch up the headlights slighly dim until I leave go and the return to normal instantly.

Its not a problem, as the windows are already closed, its just a bit odd.

its perfectly normal, its what happens when the battery is put under excess load caused by you trying to close an already closed window.

Yup normal, gets worse when battery is on it's last legs though.