Engine coolant over temperature warning

Hello, for the past two mornings after driving about a mile; I get the "engine coolant over temp" warning and the temperature gauge goes from a little below half-way (where it usually is) up to red. It stays for a few seconds then drops back down to 'normal'. It happened twice this morning and once yesterday morning. And it's only happening in the mornings! The car is fine in the afternoons. No bells and whistles at all. What is going on with this thing?