On a GL1800, I've not heard of a loose baffle either. But since it has been mentioned, it's always a possibility and would only take a second to eliminate as a possibility. However, baffles are inside each muffler and not are not inside the exhaust tips. The fastest way to eliminate such noise it the method I mentioned in post #6.
Also, since this is a trike forum, it's possible that the trike no longer has OEM mufflers.