Spice, that's normal hen behavior. She was just reinforcing her position in the "flock." I wouldn't worry about that at all. It sounds like you give them plenty of time out and really good quality treats; I do not believe this is aggression whatsoever. Even when they have their pecking order established, they still reinforce it often - several times a day, in fact.
Just a quick word of warning; it's not a good idea to flip them upside down for very long...just FYI.
Just a quick word of warning; it's not a good idea to flip them upside down for very long...just FYI.