Ian,
Don't know if it helps but I have managed to get around this in the past by adjusting the centre of the map (i.e. bringing it down).
It uses a hybrid of PHP and Javascript but it does seem to work for me.
var center = new google.maps.LatLng(<?php echo $row_rsshop['shop_latitude']+0.0004; ?>, <?php echo $row_rsshop['shop_longitude']; ?>);
google.maps.event.trigger(map, "resize");
map.setCenter(center);
Cheers
Ian