Turn Lights on - Trip meter comes on too (Rallye)

[Eddleston]

So I'm sat in the car in a gloomy garage, turn the lights on to see the rev needle. 
Finish looking at stuff, take key out, lights still on. 
Turned lights off and was sure the odometer was still on. 
Checked again and yes my odometer display activates when the headlights are turned on. Key NOT in. 
Sound right? I'm sure it never used to do that