are my toes curling under my feet?

This winter I ran a half marathon barefoot. It was much colder than I had expected and after running through many water stops where water covered the ground I wanted to stop, but decided to push on. Around mile 8 or 9 I started to get this sensation that my toes were curling up under my feet. I haven't been able to figure out what this was, but attributed it to the sub freezing temperatures of the ground. It was quite annoying and distracting, then again if I hadn't been distracted looking to see if my toes were still there than I might not have been able to finish. Anyway, yesterday I went for a run outside, I knew the ground was too cold to go BF so I wore Vibrams, around mile 6 I started to get this same sensation. When I got back to the locker room and took off the Vibrams it seemed like my toes were flatter than usual, meaning that they weren't as curled as they had been before. So now I'm wondering are my feet just going through a natural process that happens when we convert from shoes to BF or BF like running/walking? If so, I'm excited. If not, I'm wondering if I am doing something wrong and need to correct something about my form or something. If you have any advice or have experienced this before I would greatly appreciate your insight.