Chase Bank Cancelled my card Baton Rouge Louisiana

I checked my balances this morning, statement says 983.00 available credit, limit 2000.00. I go to store this evening and try to charge 14.31, I am declined. I come home and call, and am told my card has been canceled. apparently it was canceled 4 days ago. When I asked why, they say call experian, your credit changed. When I applied for my card I had a score of 640. I got card in November 2008. First 2 months payments 200.00, the next 400.00, the next 730.00, the next 580.00, the next 30.00. My minimum payments max at 28.00. I signed for a home 3 days ago. a 70,000 mortgage. my credit score 5/28/2009 was 704. I paid all cards off except chase(paid down to 1/2) and discover(paid to 1/3), during the mortgage process which took 30 days, I made no purchases on my cards, paid everything on time(as I have for 6 years). I went though only one lender, 1 credit check for pre approval, and one for loan, within 15 days of each other. What could have possibly caused this? I only needed half what I had been told I needed as down payment, so it WAS my intention to make an additional payment prior to my due date, to have paid more off. In summary, I have had card for less than 9 months(my oldest card is over 8 years old on record), my credit score went UP, I paid on time, always more than asked, just as I buy my house and have to move, my card gets canceled, and I haven't even been notified.
Oh yeah, I have been employed by same employer for 9 YEARS and 8 months.

Psychomamma
painesville, Ohio
U.S.A.