Me think you just got baptised into the Church of Tarptent.

There are two reasons for misting under silnylon :
1) the rain is knocking the inevitable condensation off the fly . ( This happens with double wall tents as well , but often enough it means that the top of the inner gets wet).
To remedy ,wipe the top down every few hours. I keep a kitchen cloth handy for that.
2) when the rain drops are big enough to hit the fly at a speed that exceeds the waterhead (1000-1500mm for this type of silnylon) some drops will penetrate causing the misting.
With cause number 2 you can also get number 1 as a bonus.

With a double skin tent once the top of the inner gets saturated it will drip on you and there is nothing you can do about it...( not quickly/easily)

As a suggestion, to minimise No 1 , keep the (mesh) door open if you can.

BTW, you are much more likely to get the bag wet from touching the walls than from misting. Most sleeping bags can cope with the occasional spray.

Franco