Nah, that would be what every other ruthless and calculating leader would have done. The thing is, Dany was never build to be calculating. Her character has been very different from others who wanted the throne.
The way she takes the cities in Slaver's Bay does show she's a calculating (and ruthless) leader. She blindsides the Slave Masters of Astapor, tricks the military leaders of Yunkai leading to an easy victory and for Meereen she not only doesn't execute the men who she's just learned have betrayed her but uses them in a mission that allow her to take the city.
Signature goes here!