I haven't actually looked at changelogs or anything, but this happened once after hovering over the preview. The image faded out back to the normal image after about 2 seconds. Did it a few times then stopped.
I don't see the image anywhere in the folder, is this a coded link? xD
i.imgur.com/SrjNy1J.png
Edit: Image isn't showing up, so here's the link instead. (And the server is acting wonky now...)