Relay buzzing during cold starts

Hello people,

I have a MK6 Escort SI with a 1.8 Zetec.

I've noticed that when a I start the engine after hours without driving her I hear the relays buzzing and then the odometer, wich is digital, goes out and then returns to 0, the TRIP not the total wich always display the correct miles.

¿Has anybody had that problem?, any idea or suggestion is welcom.

Thanks,