It is possible, this could mean that you have a circular reference issue. If you close the original project (must be closed to replace assets) and migrate the asset back to the original project and replace the assets with the ones that are not giving errors do you still get the warnings?
I have been looking into the issue, however I have not been able to reproduce this on our end. Could you try updating to 4.15 and let me know if the issue still occurs in the latest build of the engine?
Unfortunately, without a solid repro case for this issue on our end, we are unable to take any further action. Warnings can typically be safely ignored in packaged games, for the most part. If this issue ends up affecting functionality in any way, feel free to leave a comment to reopen this thread and provide as much information as you can so that we can reopen the investigation. In the meantime, without a way to reproduce the issue locally in a clean project, we will be marking this topic as resolved.