This is a side effect of  [this][1]:

> For all posts made on or after [August 17 2010][2], any image urls in
> the form of `i.imgur.com` were changed to `i.stack.imgur.com`
> network-wide.
> 
> This means, if …
> 
> - your post was made on or after **August 17 2010**
> 
> - **you *MANUALLY* uploaded something to imgur, that is, outside of
> clicking the 'add image' button in our editor**
> 
> - your image URL will be broken and you'll have to manually edit it
> back to the old `i.imgur.com` form
> 
> (please note this also implies *your image will disappear after 6
> months*, unless you [happen to own an imgur pro account][3] for your
> own personal use..)
> 
> Sorry, we assumed that 99% of users would be using the default image
> upload support provided by the editor, so those users who deviated
> will be affected.



It would appear that John T uploaded to imgur, but did not use the Image Uploader, hence the image was not stored under Stack Exchange's imgur account. 

The bad news is that the *original* image has also been deleted, leading to a image link rot.

<sub><sub>which reminds me, I need to scour my previous posts and transfer them to Stack Exchange imgur account </sub></sub>


  [1]: http://meta.stackexchange.com/questions/95732/images-manually-uploaded-to-imgur-are-not-displaying/95734#95734
  [2]: http://blog.stackoverflow.com/2010/08/new-image-upload-support/
  [3]: http://imgur.com/register/upgrade