I would be very, very surprised if anything would happen after only 3 days, but yes, it does almost look like a male flower starting to emerge from the centre top of the flower.
Maybe the plant is a "regular" hermie and the fact you recently sprayed it is pure co-incidence?
STS usually takes a few applications and about 2 weeks before anything happens and you normally have to spray an emerging branch that has not begun flowering yet, but mysterious things can happen.