After testing it a bit just now it seems to only happen on certain saves, and only when clicking the wall picture. I don't have any explanation for that, but I can get a video of it if you want.
Then I know exactly what it is, haha. The wall picture displays the last picture of her you stumbled upon (depending on the choice you made, it's one expression or another). I probably forgot to make some pic the right size to fit in the gallery :I