Enthusiasm makes people protective, and groups quietly agree not to mention the problem in case it breaks the mood. The person who names it feels like the one spoiling things, which is why it usually goes unsaid until it is expensive. A concern raised early is the cheapest possible version of the same conversation.

If something is nagging at you about a plan you want to work, say it once, early, and say that you are in regardless. Be specific about the part that worries you rather than vague about the whole. And if nobody listens, having said it on the record is still worth doing.