Yea, every once in a while they want to go on a little walk-about. I have a RBTA that was happy in this one spot for about six months. Never moved. One day it went of a walk-about and stung two of my corals, causing death on parts of those corals. It now seems to be happy stuck between the back glass and some rock…until it decides to go for another walk.
You didn’t mention, were you able to save your anemone? They are pretty resilient. A friend had one sucked through a powerhead into a hundred pieces. He thought all was lost. A couple weeks later he has a bunch of baby anemones popping up around the tank.