Does anyone know what a green flashing SET light on the dash means?....I have never seen this before...It came up after driving only a few miles today....However, when i turned the car off and restarted it, it did not return....The only thing i can think of is that it might be related to setting the cruise control speed but I have never used cruise control on my car, a 2001 QX4....Should i be concerned enough to take it to my mechanic immediately?

This most likely indicates the failure of either the brake lamp switch or the cruise control cancel switch. Ensure the brake lights come on when you step on the brake to start with.