Thanks for the quick response both of you.
I think you're probably right and it was a combination of nerves and fatigue, which hurt my wrist snap and my ability to spring up to the ball. My ball toss felt pretty good the whole time so I don't think that was it. It had been a while since I'd played a set and 2 sets was a little more taxing on my body than I realized. I'm going to try the wrist curles and also try to not spend so much time on the computer, so hopefully that'll help as well. Thanks again for the help.