Derivative images regenerated every image view

I updated the image module to 5.x-2.0-alpha3. Since then my image galleries have been broken. Going to an image node results in:
- your_image_file's derivative image was missing. The derivatives will be rebuilt to regenerate it.
- The derivative images for your_image_file have been regenerated.
- your_image_file's derivative image was missing. The derivatives will be rebuilt to regenerate it.
- The derivative images for your_image_file have been regenerated.

That's right. It appears twice on every image node. I've checked the file. It's there. Not only that, but my files table gets a new entry every time I refresh an image node.

I haven't the slightest idea what could be causing drupal to not see the derivative images. They're being displayed and the timestamp on the files are being updated with each reload of an image node so I know the directory is writable.