I've had the same issue with my maps in the past. As Rossko mentions
there are multiple solutions.

I went with someone's suggested approach of hiding the map/div from
view via positioning and css (see example below which will require
some tinkering).

.div-hide {
position: absolute;
left: -10000px;

}
Map only partially loading (Missing tiles) & Marker is not centered - Google Maps API V2 | Google Groups