As he pointed out that was most likely due to him being surprised and caught off guard, who here can say they have never dropped something after being caught of guard/surprised?
Nothing pointed to "losing muscle control" if you ask me since he shrugged it off moments later and regenerated.
Hahaha!
Then explain why his body flinched, his head jerked, his tightened hands loosened, his face turned into agony, him falling backwards, why he ran back to the edge, and why he was upset she shot him?
That's rhetorical.
It's because he FELT it.