Why is someone always smiling creepyly? It scares me!

My tutor who’s guiding my final project in college is always smiling when he’s talking to me, like ALWAYS, and he smiles like he’s afraid of ANYTHING would go wrong or any confrontation. It also seems like he’s known me well for a long time or we’re good friends but I don’t even know him, neither do I like him, it’s creepy! Even I’ve done a bad job or he’s criticizing me he still got that creepy so f_ing friendly smile which he himself probably even thinks charming or thoughtful knowingly or maybe he’s scared deeply inside or something..It freaks me out. And I don’t know why I care so much.
Does that mean he’s hiding his depression or anxiety or something?