Thanks for all the comments. I requested the miles, and I got the following response:
Dear Mr. hungarianhc,
Thank you for your recent request for Delta mileage credit. Unfortunately, I
must respectfully decline your request for credit because your flight occurred
prior to your August 24, 2009 enrollment date. In order to be eligible for
partner back credit, you must be enrolled and active in the Mileage Plan prior
to your flight. If you have any questions, please contact Customer Care
directly at 1-800-654-5669.
Sincerely,
XXXX XXXXX
Customer Care Representative
Oh well... I guess I'll just have to credit these miles to DL...