No problem. It isn't like the update contains some awsome new feature.
For future reference, when you want to move a rented movie on or off the iPad, you connect it to iTunes, select it in the Devices list, then go to either the Movies or TV Shows tab at the top of the screen (depending on what you rented). You'll see a move button beside each rented show pointing to the iPad or iTunes list, whichever list it is not on.
