Did you also have numbness going down your arm, from the elbow to your pinky and ring finger? If so, you probably had Cubital Tunnel Syndrome. I had this for about a week when I was training for my first century ride. The ulnar nerve comes around the elbow and enters the Cubital Tunnel, just distal to the elbow. It gets pinched at this point from hours of having your elbow somewhat flexed. It is becoming more common with many people who use their smart phones so much. Picture yourself using your smart phone as a computer instead of a phone. Your elbows are at an angle just larger than 90 degrees. That's a similar position to our arms when cycling.
I saw an orthopedic surgeon as soon as possible and also had nerve conduction studies done by a neurologist to see how much damage was done to the ulnar nerve. I was really scared, considering I use my hands for work. I treated the condition by wearing an elbow brace at night to keep my elbow straight. In all honesty, I just took a short length of 1 X 2 wood and loosely wrapped an Ace bandage around my arm when I was sleeping or lounging. This helped. I also no longer allow my elbows to be so flexed when I'm riding. This does put some more stress on my shoulders, so I try to place my hands in different positions every few minutes.
If you didn't have numbness going down your arm, then I hope this is helpful to someone else.