After having my cracked radiator replaced, the car ran fine for a little over a month. Then, one morning my wife noticed the "check coolant level" warning again. We added additional coolant and she drove it to work. When she was about to drive home, a puddle of coolant was underneath the car (driver side)
I added some coolant this morning and started the car (cold start) and waited till the engine warms up, but no leak. Apparently, as I was about to turn the car off, the coolant leak was coming from the resovoir tank (top lid) It looks its leaking out from the pressurize cap.


Update: I checked again this evening and there's still no leak underneath. It appears that it will only leak out of the reservoir tank, when the engine is warm and running. Any ideas what may be causing this?