You cannot consider an openly carried weapon to be secure. I don't care who you are, you cannot be in 100% Full Condition Orange Sheepdog Ninja mode, someone can get a hand on your piece and no one knows how it may end.
Just take out your wallet and pay for your slurpee and newspaper while open carrying, then tell us the person behind you at the counter couldn't have got his hands on your weapon while you're taking care of the transaction and the cashier was chatting to you.