Most probable is a flinch, however not all flinches are caused by anticipation of recoil. Loosing track of the target, or loosing focus on the target or moving on the target before focus is established can cause this symtom. Recognizing a flinch is easy, but diagnosing the cause would require someone with instructor ability. Think about a lesson with a good instructor before you try self treatment.
Yep but you forgot one other very real cause of "Flinch"
Noise yes the anticipation of the bang causes a flinch in many cases.