That's called Guttation..
Guttation is the exudation of drops of xylem sap on the tips or edges of leaves of some vascular plants, such as grasses, and a number of fungi. Guttation is not to be confused with dew, which condenses from the atmosphere onto the plant surface. Guttation generally happens during the night time
Thanks Hammer for the great answer, it makes a lot of sense since my growroom is full and ventilation is not enough (still waiting for a fan i ordered one month ago)