Help please (dash lights)

I wuld be grateful if anyone can reassure me with a query on my 996 C4 (2001 model). I noticed yesterday that when I turned the ignition off the digital speedo display, the odomoeter display and the display to the right of the digital speedo (can't remember what that one is off hand) all remained lit up. This remained the case for a few minutes and then they went out as normal. I noticed that if I set the alarm then the lights all went out as normal. I've only had the car for a couple of months so not sure if this is always the case or if it's just started doing this. Earlier in the day I had had the Tracker checked/serviced so wasn't sure if something had been accidentally adjusted in the electrical set-up by the Tracker engineer. Is this is a normal scenario on a 996? I did a bit of a search on the web and it seems that some earlier Porsche's had a delay function where this happened and then the speedo light switrched off after 4 minutes. But I can't find anything that suggests this is normal for a 996. Just for clarification, the inner door lights dim as normal after approx 10 seconds or so but the speedo lights etc remain on for a few minutes. I appreciate this sounds like a small issue but as I don't want to risk the dash lights remaining on indefinitely and draining the battery whenever i leave it parked up. Any help gratefully received. Many thanks

Sounds perfectly normal to me. The odometer, etc, always goes out when locking the car, but I've never quite worked out the randomness of it otherwise. Apart from the two hour and 72 hour load shut-offs (described in the manual), I suspect there is another after about 10 minutes which controls this function.