Confusing upload to gallery in version 2.5?

Hi all,
I’m a bit miffed as to how I easily upload an image to the new gallery feature in wordpress 2.5. I know if you write a post, you can upload an image, and save it. If I now create a Gallery page using the [gallery] code, then I see my image. But now, if I go back to write a post, and upload another image, I don’t see my gallery page updated. I find this a bit confusing? I see my images in the media library, but they don’t all show up on my gallery page…as if it’s not being updated. Is there a less confusing way to do this? Like put an upload button on the wp-admin/upload.php page?
Any advice or help you have is appreciated. Thanks!