OK - just went to check up on the anemone and in just the two hours since I asked the question, the anemone let go of the front glass and has moved to some tonga live rock. Lights will come on soon so we'll see what happens. I did not realize that these creatures could move so quickly!
Thanks for the advice on the path, I'll keep an eye on it. Fortunately I only have a few corals and I haven't glued them down yet, so if the green bubble anemone gets close I can move the corals temporarily.