2005 Dodge Caravan - out of warranty

Was little over 100k miles so I had my coolant changed at Jiffy Lube. About
a week or so after that, I pulled into my driveway and shut off the car, and
heard Niagara Falls coming from under my car - looked and the overflow tank
was spewing out coolant. The thing is, it looks like they overfilled it
because I still have enough coolant in my radiator and overflow tank. That
was the only time that happened, and my car has never overheated. I thought
maybe the thermostat was sticky too.

The question I have now is, when I start the car, from inside the car with
the windows rolled up, I hear water running around the sterring column/dash
someplace. I don't think this is normal as i never heard it before, but I
don't have a clue what it could be. Car still never over heats, drives
normally too. I don't see anything leaking, and I don't smell anything. The
oil is normal, the coolant is normal (no head gasket issue).  I just hear
water (fluid) running. Heater works fine. AC works fine.

Any ideas?

-Tom