Originally Posted by lin821

To the best of my knowledge, transactions used with a PIN for all American credit cards, are treated as cash advances, as other posters had said. Cash advance transactions carry no grace period and start generating interest charge from the date of the transactions. That's why never use you American credit card w/PIN, either to withdraw cash from ATM or conducting a transaction. (Unless you have an emergency.) Debit card is a different story though.

It seems a common confusion between Chip&PIN credit cards and credit card with PINs, especially when using credit cards among US and the Europe. It appeared to me OP had used PIN with the card during the trip. I would advise OP to double check with your card issing bank and verify ASAP if those PIN-used charges had been processed as cash advances and pay all of your balance off right away. Having both cash advance and normal credit card transations on the same billing cycle will trigger not only interests but also financial charges if the whole charges are not paid off.