I have persistent numbness in both hands, but…
Right hand. I was hit on the wrist with a 14lb sledgehammer when holding a stake in the ground, years ago. Ouch. Turns out I have nerve damage, similar to carpel tunnel. bummer
Left hand. I bruised a bone in my wrist, had a bone graft and arterial transplant. Ouch. Now I have to do pushups using dumb-bells on the floor as I can’t ben my wrist past 45 degrees. Bummer
My solutions have evolved to the following.
Gel inserts on my handle bars. (2 layers)
Up to 3 layers of foam cork bar tape
Change hand postions often
Raise my bars slightly, to reduce weight on the hands
Ride often, but less distance each time
Best gel gloves I can find.
Type at my computer less
since you only got it once, on an uber long ride, I wouldn’t worry too much. symptoms are probably temporary. If not, see a doctor.