I have a map powered by Google Maps Javascript API3 in my jQuery Mobile web application. I added a circle with black borders on it.
On one page of my app with the map directly, the map is centered correctly at the center of the circle.

But if you visit a different page and then click your way into the page with the map, the map is

Why is the map erring when I click into the page with the map from my home page, but working correctly if I visit the page with the map directly?
I could just not use Ajax to load the map page with data-ajax='false'. However, I cannot actually do this because a mobile application does not allow for non-ajax loads.
google.maps.event.trigger(map, 'resize') seems to reposition the map when I enter it into the Chrome Web Developer console, but I am not sure where to call it in my javascript.
Because the page is actully loaded via ajax (when coming from index) - the page event you are using is probably being called before the DOM is totally ready. GMaps expect the page to be ready.
Try using a different event other than pageinit. Looks like pageshow might be a good one (as it runs after any animation has finished) http://jquerymobile.com/demos/1.0/docs/api/events.html
Or maybe you could put the call to the maps resize event, in a pageshow event.