If you lose your coin, and someone else picks it up, then you've compromised not just one card, but multiple. Unless I'm missing some sort of authentication whe

If you lose your coin, and someone else picks it up, then you've compromised not just one card, but multiple. Unless I'm missing some sort of authentication when using Coin? And if that authentication exists, how would the non-Coin holder use that card? Is there a timeout that requires the user to authenticate, select a card for presentment, and holds that card in the stripe until a timeout? if not, then there's problems here.