As you may have read AMEX instituted a lot of temporary credit limits
reductions on their cardmembers and AMEX is the only credit card
Costco takes.     It looks like they've got a cash shortage because I
got one of the letters and called them and they insist thel ower
limits are "temporary" but they REALLY lowered them.  People with 770
FICO's ended up with $1200 limits, basically "frozen" at the
customers' current balance.

I posted excerpt from an article brelow.   It sounds like AMEX was
worried they did not have enough cash to cover all their members
purchases over the next few months (read "holiday shopping season")
and so they cut of their newest and weakest members:

"On October 7, American Express revealed that they will begin
limiting
their customers’ access to credit based on both where they shop and
which bank holds their primary mortgage. While there is nothing in
the
law that prevents American Express (or any other credit card company)
from doing this, the announcement is noteworthy coming from what many
assume to be the creme de la creme of unsecured personal credit
lines.

The credit crunch is about to hit the consumer pocketbook in a big
and
personal way, starting with credit card companies looking for ways to
limit or freeze personal credit lines. The reasons for the lowered
limits are not always obvious, and they may or may not have anything
to do with the customer’s financial balance sheet. American Express
would not reveal the stores or banks that they considered “risky,”
but
if you happen to have an association with one of them, however
tenuous, look to see your credit limit lowered or arbitrarily frozen
very soon... "

http://citizeneconomists.com/blogs/2008/10/10/credit-crunch-hits-cons...

That's not really so unusual for AMEX. Even when the economy was good
Amex had a reputation of lowering credit limits. Happened to me. Went
from about $5k to about half that. I didn't really use my Amex card
though which may explain why they did it.

they did it to me, perfect credit and when i went to put something on
the card, said it was denied, called and the customer service person
said my limit was frozen. i checked it online and it still shows
available, then i got balance tsfr checks from them in the mail. so,
the right hand doesn't know what the left is doing. anyway, my
prediction is the credit cards are going to sink the economy...forget
gm, chrsyler, etc., the credit card hit will be the worst, because
there is no precedent for this one. probably good they are lowering
limits