If you treat in tank correctly there is no issue. Vinegar bath everything and starting over is silly. Just need to be diligent in observing the tank and remove the pest as soon as it is identified.
They don't spread that fast. Poking them or slightly damaging them is what causes them to release spores and spread faster. Kalk
paste mouth first and then cover the rest entirely. Make sure the paste is thick enough to stay where you put it.
No need to freak out when you see just one or a few.