I work in a windowless office. My wife got me a plant to spruce up the place, it's supposed to be watered once a fortnight and need very little light.
It sat in the dark in the weekend and when I got it it had these water drops on many of its leaves. What's up?
Plants evapotranspire.
Fancy word for what you might call "sweating". Normally you won't see it because the humidity evaporates as quickly as it builds up in and on the leaves.
Water moves from the roots out to the leaves to transport itself and nutrients. The excess generally doesn't go back down, but instead evaporates through pores on the leaves.
I'm not sure this is that, but if the air in the office gets cold/humid, you'll see the water bead up on the leaves instead of evaporating.