Well grammas are also notorious for Brook, particularly at this time of year. They typically come from Haiti where it's hotter than it is here, and the stress of capture, handling, packing, shipping and etc., makes them very vulnerable.
And of course clowns are very prone.
I'd be concerned that the blenny and/or goby end up as carriers - I've seen that before - had it happen to me and I thought it was all gone, a goby never showed symptoms and wasn't treated... later when I put more (prone) fish in the same system, the stuff reared its ugly head and the goby never showed it.
Treated everybody, including the goby - problem didn't return.
Might be a coincidence, but I'm inclined to err on the side of caution.
If you don't treat the fish, don't be surprised if it comes up again down the road.
QT/treatment and QT (for observation and treatment if indicated) of new acquisitions is always recommended.
Jenn