No, it is perfectly OK to not be glad. we live in a world where we are bombarded by images of happy, happy people and happy, happy lives. The TV here is full of commercials for drugs to make you feel better. Capping all our sad feelings can't be good all the time.
If someone needs help with debilitating depression or anxiety, that is one thing, but often feel like if we are not smiling 24/7, the world sees us as negative and saaaaad people.