Removing one shoe and one sock

Sonik is an unusual and unique baby (she sleeps sitting straight up, she crinkles her tiny button nose, shows eight pearl white front teeth and blows air hard to scare you, and does over a dozen other very unusual things...) but what is up with constantly removing one shoe and one sock? Is this an unusual behavior or what? I cannot explain it, but we are constantly searching for her left shoe and her (left) sock. I have examined the foot practically under the microscope to see what could possibly prompt this, was something rubbing or irritating her tiny porcelain foot? Correction: Sonik has peasant feet - olive colored, wide and her soles are no longer baby soft. This is a mystery that I will need to solve soon... I cannot continue to walk around with the baby that has only one shoe.