No it is not a reflex action

The difference between reflex and voluntary action is that a reflex occurs naturally in response to some sort of stimulus and voluntary action is something that is consciously carried out. An example of a reflex action is gagging and an example of voluntary action is flinching when someone is going to hit you.

Reflex action is the instant reaction of our body while hormonial action takes more time to react

The verb "trow" means to think or believe. That is a conscious action, not a reflex action.

Reflexes are uncontrollable movements that happen almost instantly in response to a stimuli. A reflex arc, a neuronal circuit that controls reflexes, is where reflex activities takes place.