Dealership forgot to put coolant cap back on

I took my car in for  service recently
and as I was driving it home, the
coolant temperature light comes on. I
pull over immediately and call the
dealership. I notice at the front of the
car there is green fluid dripping out.
They sent a mechanic over and the
cap was off as it wasn't tightened
properly. He refilled it and I drove off
and my car seems ok. I didn't notice
anything out of the ordinary when I
was driving it before the light came
on, which was about an hour and the
car seems ok. Should I get the
dealership to inspect it to make sure?
What kind of damage could have
happened?