I think, once you are done with displaying the contact div, you need to call the resize
event on google map.
var map = new google.maps.Map(selector, mapOptions); //Initialising map.
var currCenter = map.getCenter(); //Get the center location of the map
google.maps.event.trigger(map, 'resize'); //Trigger resize
map.setCenter(currCenter); //Setting the center in resized map.
Should be easy. Make sure you call this code after your contact div
is loaded/resized/animated completely.
Let me know if it works.