Yes, my SPS get exposed to air when I'm setting new frags, obtain new frags, do water changes, etc. It won't hurt them at all. They are often exposed during low tides for hours at a time. Most of the time, when things like Acropora and Montipora get close, nothing happens. They usually need to touch. But things like a Hydnophora is able to send out rather long sweeper tentacles and kill nearby corals.