I'm going to go against the grain with the previous posters and say this:
I was an Uber driver a few months ago. I had numerous people ask me about tipping. I clearly stated to them, Uber says tips are not required. I had people say to me, I thought tips were included in the fare. I clearly stated to them its only for UberTaxi and not UberX. People who asked me these questions often left me a tip, they insisted.

I'm going to disagree with the fact that you should email Uber and request your money back. As OP stated, you made a personal choice and the driver likely appreciated it.

It is a personal choice to tip or not to tip, but I think it's rude to ask Uber to refund you the money. I'm not sure what the policy is but that money could be taken away from the driver on his weekly check AFTER they took the fees away from him. I've read Uber has done this to others.

Honestly, drivers appreciate tips and rate you higher. Many drivers, not including me will rate based on tips. I only rated low if you messed with the car or insulted me.