How do people guess I'm fresh to a MSQ dungeon?

It's happened a few times where I get to the end of an important dungeon and someone says in the party chat, "And that's the end of X expansion" or along those lines. Do people just generally say this or how do they know I'm actually new to that dungeon? I mean, I am a sprout but a returning sprout so I'm not sure that's a complete giveaway is it?