There is usually case law in individual states regarding this (which means people have been arrested for their gun becoming accidentally unconcealed
). Especially if it's an OC state there should be some history of laws regarding what defines an openly carried firearm.
We had one guy here in MI, was OC'ing (and had a CPL) and was talking to the police, when the officer looked down and noticed his handgun. He was charged with failure to disclose a concealed firearm and his CPL was taken away for like 6 months. Charges were dropped if I remember correctly.