Agreed.
Although, honestly, you all probably saw that coming. XD It's a good idea, even for minor events that you guys want to do. Minor events have no relation to the story and are unlikely to carry consequences through the rest of the ship/crew's lifespan.
Even if you want your event to be a secret, don't make it an unexpected surprise. Literally, all that needs to be posted is, "Guys, there's an event on XX/XX/XX at XX:XX!" so the contents can remain as secret as you want them to be.