My scorp is also weird at times.I can even say I'm 100% sure it is an emp.
Not all emps are the same, you probably bought a more agressive one.
I have 50+ emps, some more agressive then the other, a few are not for handling.
I mean, its aggressive when I get close to it, but I've seen a feeder cricket jump and rest on my scorp's head, as well as crawl right into my scorp's head without even being attacked.