It completely depends how it is said, the tone and the non-verbals. It can be creepy and sexist as well. Some component of it is not just that it was a man vs woman but that it was a manager. Then it can feel patronizing. "Come on! Amuse me with your smile. I don't want to have frowning reports. If you don't smile, no good review at the end of the month" kind of idea

Besides cheering someone up by telling them to smile is like telling a quiet person that they are so quiet. Haven't seen that ever help except make the person even more quiet.