Why is the android in the home screen so emotionally unstable?

When you are in the home screen of "Detroit: Become Human", there's an android that talks to you.

When she talks her facial expression is coherent with what she's saying. But as soon she stops talking her expression completely changes, suddenly, without any evident reason.

She becomes worried and kinda astonished.

Is there any explanation for this behavior?
Honestly I think it takes much of the reality fidelity out of the character.

I have not yet completed the game but I think from what I've seen it ties in with the plot. As the game progresses she says new things (or possibly just over time you hear more things). One of the things I have heard her say which I think would explain this and ties in with the main plot is:

"I detect a malfunction in my program. This is worrying."

Having just finished the game after you have

the android on the home screen basically says that watching you play the game has made her a deviant. So as the game progresses her facial reactions are deliberately intended to show you that she is becoming a deviant something that has been seen in the game to trouble some of the androids as they come to realise it.