I would have done it exactly the same way in that situation. Thinking about having ISO4000 today and only complaining about some nise is fantastic.... I still only managed 1/100, which in my old hands is approaching my limit! I could have opened it up more as I used f5.6 for better dof. ...
1/100 is already challanging for the fine details of dragonflies. Khudos for a steady hand and HIS of the macro.
f/5.6 with macro closeup delivers such a shallow DOF that I would have thought more about going Av with f/8, fixing ISO at 2000 to 2500 and firing some bursts of pics hoping that the HIS would get at least one sharp
That's one of the advantages of digital photography over film that I must get more used to: 10 pics more are only more time in post to decide and delete