Thanks everyone,
After reading all explanations.. it actually makes sense
After some more investigations it seems that my condensation was coming from coolant cap. I have the new cap (04 version) but the threads on the tank were old, also the plastic cover that you put on the tank was kinda stopping in one of the plastic ribs on the tank which made it impossibile to screw the cap tightly.
I cut the plastic cover a little and added some PTFE tape on the threads on the tank.. and after 2 hr drive no more condensation so far.
Thanks
Sasha