Mystery coolant leak 530

Driving around no probs, stopped and came back to the car while it was shut off, trail of cool blue. Opened the hood, leaks in the heater valve area from underneath but couldnt see any leaks under hood so I drove it home and on ramps. nothing. level is lower but nothing major. All new hoses and re-tightened most incase. I will tighten the other ones that are almost impossible to get to but still, no signs of leakage.

An clues?