In my experience there can be many reasons for attitude change:
-Illness
-Sub par conditions (i,e, heat, humidity)
-Diet
-Shedding
-Handler mistake
-During breeding
I know the above list is kind of general but speaking from my own personal experiences with some of my Elaphe species these have shown to be a contributor to abnormal behavior. And keep in mind it may be none of the above and the snake could just be having a bad day
Hope this helps