No not on the day that i bought the wonder, i did collect again the next day because i had no happiness bonuss and tought my wonder needed some activation or something...this time i had an event.
However i'm still well below the 25 population per mile.
Something than that just happend to come up at the same time that i bought the Moon Base, without my knowing and that took away +5 happiness, making the effect of the Moon Base 0.0?
Could be, but i think this is very unlikely.