If anything why didn't Tsukushi end up oh I don't know a blushing hot mess?/ It's just (-_-)
Which she did just after the kiss if you paid attention. She even wobble, meaning she is a bit shocked.
This is not a normal reaction. My God.
There is nothing as "normal reaction". People react differently at the same situation. Just because she doesn't reactlike you wanted her to react mean her reaction was "not nomal".
It's something to be upset that the author seem to stall, it's another to re-write what happen in the chapter, which was not even that long to top it off.