Originally Posted by
groovestew
...I should mention that it was very cold (just above freezing) and my hands were quite numb from inadequate thermal protection which may have been a contributing factor...
I suspect the cold is the real issue. I had the same problem on a cold 200k. When I got my 2nd flat, I was afraid I'd have to dnf because I was struggling so hard to get the tire off and on. I had numbness in my thumbs that carried on long after the ride. Since I had no similar issues on longer rides(when it wasn't cold and raining!), I chalk it up to the cold. I'll never get caught without good gloves again.