Oh, Joe! I understand your pain as I too dislocated my hip after revision - they had to anesthetize me just to move me out of my house on a stretcher.
I'm afraid the answer to your question is "Yes" - 180 degrees is more than 90 degrees, and the muscles and tendons just haven't healed enough to hold everything in place. After this experience, you probably won't need anyone to tell you to slow down. I think it was nine months before I could safely do that ITB stretch.
You are luck they could do just the closed reduction. The next day, my surgeon saw me and did a manipulation under anesthesia that told him I was at risk for another dislocation - led to a 2nd revision so he could insert a larger ball (all has been well for 14 years now!