After answering this one, I noticed that this user's flair default theme's reputation is 100 off.
Could be a bug?
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I was not able to reproduce with my flair, maybe the classic version was last accessed and cached separate from the others 100 rep ago. Then when this image was taken, the classic used the cached version while the other three were generated with the new higher rep.
Flair images are not guaranteed to be generated at the same time. For example, it is likely that someone will have a flair image using a specific theme on their blog.
This can cause the following: