It is a normal phenomenon called guttation.

Roots pull more water than the plant can use at this moment - and the plant exudes some of it through the pores.

I think it depends on the time of the day - plants evaporate more water in a day time - so they do not need to do it - and in the night time they do not evaporate as much - so the will "spit" some out. Probably it is better to water in a morning anyway to avoid it - but it is not harmful.