Can corals being "close" but not touching ignite chemical warfare?

As i transition to BB and cook my tank, ive been keeping my 35 or so frags on a peice of plastic crate that you usually see at lfs. The frags are about 1-2" apart and not touching, yet things are receding/closing. Even my easy stuff like my kenya tree/zoas. Are they sending chemical defenses because of the close vicinity? I thought since alot of well eatablished and populated reef tanks have corals tjat even touch but are still open and thriving, this wouldnt be an issue. What do you guys think?

Thanks!
Scott