Goby and pistol shrimp

I have, or had, a paired yellow rose goby and candy striped pistol shrimp in my tank for 2 months.  They made a burrow towards the front of the tank and I was so happy that I could see them come out for feedings.  Otherwise, they pretty much always stayed hidden, although the goby would come out occasionally on its own.  Now I haven't seen either one for several weeks.  I am hoping they aren't dead, but of course I realized that's the most likely scenario.  I was wondering if there's any likelihood that that they changed burrow location to a spot where I can't see them, or do they tend to stay in the same burrow?

My pistol shrimp is never idol. Even after building what I would consider the best burrow in history it begins digging somewhere else! To be honest it gets a bit aggravating to wake up to a low coral covered in mine tailings. Be patient I bet they show up soon.