Very cool info, thanks Vsnsofadrgn.
It's been roughly a couple hours since I posted, and sure enough they emerge from the rock.
The Goby has half his body sticking out, and the Pistol just came out for a minute and I prob scared him back inside the cave.
Another funny thing, even though the Pistol Shrimp was hidden, I could tell he was hard at work. White sand was shooting up from under the rocks in the area that he is digging for like a couple minutes, partially clouding up that side of the tank. haha, that was pretty sweet to watch... picturing him inside digging away.