Fallout Shelter drafty in here, problem?

So I was playing Fallout Shelter and one of my dwellers said it was drafty and someone should check the vault door seals

Is this a real problem or just something they say, if it's a problem, how do I fix it?

This is just something they say, a bit of a joke considering how secure the vault doors are; they were designed to protect the dwellers from a nuclear war.

There's no need to worry about it.

When you zoom on 2 dwellers in the same room they show some 2 part dialogue, usually a question and answer. Nothing they say is really useful, but sometimes can be mildly amusing, such as:

• Can you help me with my crossword: lives in the wasteland
  • try "nitwit"

They also sometimes refer to their state or the room state like

• "have I told you how happy I am to be here"
• "smells like someone died here"
• "I have the perfect work assignment. thanks overseer!"
• "Great! we maximized production!"