You can use this URL to monitor the Ajax response for the Paypal review page:
NOTE: I didnt realize how much this forum software sucks, but the text shipping_method in the url keeps getting a ; (semi-colon) injected into it. Just remove it when copy/pasting.
As you are checking out by Paypal, you can refresh that page periodically. You will see the right charges ( free shipping ). Even when you leave your site and enter Paypal’s the prices are still accurate. At the step where you are returned back from Paypal, if you refresh this page, you will see the shipping price change and become inaccurate.
At this point, if you open another browser window/tab and load the cart, then refresh this page, it will show the right ( free shipping ) prices.