I found it on TIS:

Title: Positive engagement in drive position D delayed.
Number: 24 02 03 (055)

Updated: 12/2004

Vehicles: E43, E53, E83 with A5S 390R
Mfr. Dates: 2/2003 thru 11/2003

(GM5 Transmission)

Complaint: The first time drive position D is engaged after a lengthy period out of use, e.g. overnight, the transmission only gains positive engagement with a time lag (longer than 2 seconds).

Cause: Leakage inside the transmission, C1 clutch empties during the parking period.

Procedure: In case of customer complaint replace transmission as described in Repair Instructions 24 00 48.

Defect code: 24 00 90 63 00 (NOT contained in the official defect code catalogue but is inlcuded in the system).

Reimbursement is limited to 36 months/100,000km and only possible until November 2006.