Yes, the moon is functioning properly. There is nothing wrong with it. Fortunately, if something does go wrong, the moon is still under warrantee and can be replaced at no charge --- 5 billion years or 65 billion revolutions, whichever comes first.

The serious answer is that Coelho is right. The moon comes up 50 minutes later each night, and slowly works through all of its phases over the course of about 28 days (one month, or one "moon"). If you watch the moon for a month or so, sort of like you have been doing, you will get a real feel for it.

Also, if you look at the moon through a good set of binouclars, you will be surprised how much detail you can see. And if you have access to even a very small telescope, you will blow your mind looking at the moon.