Yes, it could be swollen from banging it on the glass. However, in my experience there are a few other things that could also cause the jaw to get deformed or stick out and look swollen. The first thing that comes to mind is mouth rot (Stomatitis). This is really uncomfortable to the beardie and they often rub or bang their mouths against something to relieve the pain and itching associated with it. You can tell if a beardie has mouth rot by looking in their mouth. If you see a whitish substance that kind of looks like cottage cheese then it's mouth rot. Also look at the gums to make sure they are nice and pink - which is healthy.
The second thing that comes to mind would be MBD (Metabolic Bone Disease). Severe calcium deficient beardies often have deformed jaws because the bones in the jaw lack the calcium to hold their shape and you get what looks like a rubber jaw. Often the upper or lower jaw will stick out.
Just a few ideas. If your beardie is healthy, getting plenty of calcium (especially when egg-laying) and getting UVB, then there's nothing to worry about.
Veronica
Beautiful Dragons