I just posted my corgis, and I saw this:

And now it's popping up when I go to create this post. Anyone else seeing this?

UPDATE: It seems to be attaching itself to the top-level post.

UPDATE: I was running Mozilla and installed Adblock, but that ad is still there. Huh.

UPDATE: And now it seems to be gone. This is too weird. Good thing I got visual proof or no one would believe me!