It can happen even when traveling in the US! Chase froze my M/C account after I used it on a trip to WDW, and rather than room charge with one or two big charges, charged everything individually right to the card.
I had to call them and verify about 100 charges before they would turn it back on! I had them do something to the account so it sees charges in the central FL area as being my "Second Home". But I still call in advance when traveling anywhere else.
Anne
PS--There is no limit on credit cards being taken/used outside the US. It's only the amount of currency and/or negotiable instruments that you can carry back and forth.