Yes. I agree. This is also where we learn how useful the captain is going to be.Often true - but the same idea of it being a useful headstart still applies, perhaps even more so.
Call them over, say "Remember what we talked about before we started? This is an example of the kind of unacceptable dissent that I was telling you would need to be controlled" and you're already further down the line than you would be if you'd said nothing at the start.
Had in a game recently, few instances of low level dissent. Brought skipper in with one of offending players. Reminded him of his responsibility. He was useless. Next dissent. Bang. Caution. With a shrug of ahoulders to captain as if to say you could have dealt with that and didn't use him again in the game.
Sometimes it goes the other way, and the skipper is sound and sorts it out. But we have to test the water to find that out.