The bump behind top front teeth (incisive papilla?), is suddenly red and smooth when wet. Could this be from accidentally catching it with toothbrush?

Yes. Typically we call this a pizza burn type of injury. But it can be cause by anything from a potato chip to hot coffee. It should go away in 7-10 days. If not it should be evaluated by a dentist.
Sure. You may also have bit on something hard and irritated it. Should pass without a problem, otherwise see your dentist.