Flip Animation is not consistant in size between front and back images

using the same flip animation as in the Elements, I have a view controller flipping two .png files of the same size (640 x 960) Within each image I have drawn a border and have noticed that when I flip the image, the second image gets stretched slightly downward and you no longer see the bottom border.

I've checked my .xib file where I have two views and an imagev开发者_JAVA百科iew inside each view. The imageviews are both the same size and have the same settings. I did notice that in interface builder the size for the layout is 320 X 460. Note that the first view appears in its entirety and as I flip it over and over it continues to appear as it should and the other image is clipped.

It turns out that the first view presented to the window has a heeight of 416 and not 480 as expected. I forgot to account for the added NavBar and the initial view squashed my image to fit in its entirety. I have since set the view size in the back view and am dealing with the smaller image area.