Originally Posted by
Ex Amex Card
Their antifraud systems can sometimes lock a card out for reasons known only to Amex.
I have had my card suspended when travelling from the UK to Ireland, they said the behaviour was "suspicious" even though I booked the tickets on the card 8 weeks before and paid that balance off.
I think that AMEX does a pretty good job of developing a "user profile" of the card holder. I do so much traveling, I am never asked about my travel plans and charges are never denied for travel related items. However, I have had a chase card which triggers fraud for things as minor as internet purchases. I really think that AMEX uses some pretty sophisticated statistics and profiling software.
Typically though if your card is blocked, it only takes a simple phone call to get things back in order.