I'm afraid that this is an error from some internal Storage DRS log which vCenter doesn't expose to the outside as vCenter events. Our MP is collecting vCenter events, so if there is no event - our MP doesn't have anything to trigger an alert.
I do not see any alarms on the datastore cluster itself with respect to the issue you've mentioned, so I assume that this is not considered an issue by vCenter.
However I do think we might need to monitor Storage infrastructure in more details, this is something for us to investigate for future versions of our Management Pack.
Let us know if anything else important is missing from our MP. Also, do you know if this error means something serious or it's some internal issue which is a part of the process and doesn't affect performance of Storage DRS functionality?