Drops and a question

Playing with waterdrops, always good fun if you've a bit of time on your hands.
I liked this shot, but it also puzzles me, so a question for you:

The trailing effect looks like the 'dragging the shutter' effect, but with a shuttertime of 1/60th i sorta figured the flash would sync at that speed. It looks like it flashed quicker though.

I made this using a macro lens without electrical contacts, so there's no diaphragm information/setting possible. The flash is a speedlight 580EXII, connected with an off-cam shoe cord (FC-e3 by JJC).

Now its not that i think the shot is completely lost, i kinda like the effect, but i would've guessed that it would be a straight flash 'frozen' shot (or with some movement because of too slow shutter _and_ flash), but no dragging effect.
My only guess is that the flash went off at a higher speeds (like 1/80?) for some reason. I do have 2nd curtain sync on standard, so that would be consistent.

Any thoughts?