Since you do seem to have compressed the nerve near the carpal tunnel, it's possible you had too much padding and it impinged on your nerve. If you look at most cycling gloves, they have an absence of padding right over where the nerve passes through the pad of your palm. But, in support of the shifting idea, I can see how you would put your hand on the side of the handlebars (resting on the nerve) so you can shift more readily. I'm going to try to pay more attention to this since I would rather not have my issues get worse.