When you have a problem with google map when hiding or collapsing it within a block you need to do something to fix this. A way to do this is to make gmap block absolute in position and -10000 px in left like
#block-gmap_location-0{
position: absolute;
left: -10000px;
}
and then use jquery to show it with js script
$('#block-gmap_location-0').css("position","relative");
$('#block-gmap_location-0').css("left","0px");
and finally map is fixed and working.