Code signing mystery

A customer is doing some testing with my app. Part of the app is a Filemaker file. Because he is very thorough he also did some testing on the newly released Filemaker 17. He sent me the below screenshot:

Has anyone seen a code signing warning for a file before? Of course, even for testing the app is signed. But it’s not even possible to sign files.

sounds like the file is marked as executable with file permissions.
I see that often with shell scripts.

Very good idea. Thanks, I’ll check this.