7.7.0 - SQLTags$ClientSubscriptionProxy Error

We are having some problems on a redundant pair of servers. Many of our issues have known causes, but I logged on today and found a log full of this message:

3:55:45 PM 	SQLTags$ClientSubscriptionProxy 	Client subscription proxy got a tag change event after it was shut down.

This was being logged several times per second and had been going on for at least several hours. Based on other posts I restarted the Gateway which did stop the messages.

I never saw a clear cause listed in other posts. Is there something I need to be aware of to prevent this in the future?

Really strange. We have exactly the same problem.
Running 7.7.2 here.
Started this morning… I don’t know the exact time because we have more then 4000 of these messages.

Edit:
After restarting the gateway it has been fixed. But it would be great if we know how this occured.