There is a new Google manual action that you need to be aware of named "image mismatch." This manual action is when your images on your site don't match what Google is indexing and displaying in their search results.
Google has a new help document on this over here where it reads:
If you see this message on the Manual Actions page, it means that some of your site’s images may be displaying differently on Google’s search results pages than they are when viewed on your site.
As a result, Google has applied a manual action to the affected portions of your site, which will affect how your site’s images are displayed in Google. Actions that affect your whole site are listed under Site-wide matches. Actions that affect only part of your site are listed under Partial matches.
An anonymous reader sent me a screen shot of the notification he received for this on his site:
Images from this site are displayed differently on Google search results pages than they are when displayed on this site.
A form of cloaking or something less intentional like using hotlink protection techniques to prevent or discourage users from stealing your images?
Have you seen this manual action?
Forum discussion Google Webmaster Help.