I was refreshing a question, then a chat widget appeared in the sidebar at random. In it, I noticed that one particular gravatar was showing up oversized:
This particular user, I notice, actually has a Gravatar; it seems the image somehow failed to load and is being replaced with an identicon, and this identicon isn't showing up in the correct size. Needless to say, I haven't been able to reproduce it. What's up with that?