The only issue, which is not really an issue, is that R2012b doesn't error when the index is greater than the number of images in the stack, it simply opens rem(index/# of images) until it reaches some large number which I'm guessing has something to do with the number of bytes of the file, and then it errors.
The reason I had a problem was because the code I received opens the images by running a loop incrementing the index by 1 each time until imread errors. It's a really stupid way to do it, I agree. I'm going to change it. Also imread(...,'Index',1) creates the correct image, I was just visualizing it with image(...) instead of imagesc(...) which was stupid of me. Dang.