(A Note to Self)
You get an inexplicable direct deposit from the US Treasury. What to do?
Don't try to call the agency responsible since they'll just say, "Did you talk to your bank?" (which you already did, which pointed the finger at the government agency).
They'll say that it sounds like an error was made. You'll think silently, "ya think?"
They'll recommend the time-honored method of error-correction: procrastinate and see if it'll go away on its own.
And don't spend the money in the meantime.