Those three types of soft coral close up very quickly if their environment changes even a little bit or if they are blasted with a surge of water. Its normal and nothing to be concerned about.
Instant Ocean salt will leave a film of slime on the sides of whatever container it is mixed in. A clean glass of water sitting on your kitchen counter top will also collect air bubbles after several hours. I'm no chemist but I think its caused by oxygen diffusing out of solution and clinging to the friction of the clean surface. Again, this is normal and nothing to be concerned about.
