Okay, I did a wee bit of reading on this.
The fact is that when dealing with fat (your face chub), you can't work on just one area. That is not the way things work. You can only reduce overall fat.
Doing some sort of face exercises may actually worsen your condition. If you tone up your face muscles, that could possibly push out that chub even more (although it's unlikely).
The sad but true answer: exercise and diet. You'll probably want to focus on your diet but have plenty of cardio calorie burning goodness.
edit: Got most of my info from
http://skinnyguy.net by the way.