I always check for this type of thing when I can't figure out the fussiness! Especially now as I am in the middle of severe post-partum hair loss. We co-sleep and DS2 manages to get some of my hair in his hands during the night, every night! In the morning, I work his little hands open to get the hairs out.
In our childbirth education class before DS1 was born, the instructor told a story about a situation she had witnessed just like that, where the parents could not figure out what was wrong and it was a hair wrapped really tightly around a toe. I never forgot that.