If it gets over 81*F, I also urge you to think of a solution to get the temperature down. Our silly little crabs will be attracted to the heat, but will not register that it's getting too hot, and will cause themselves heat damage by staying on a heater. I lost one crab for this very reason. He dug down on top of an under tank heater (he was on the glass below the substrate) and he suffered heat damage which he died from several weeks later.
It isn't apparent right away, and heat damage is irreversible.
I now have a thermostat attached to my UTH to keep the temperature regular and it never gets over 81*F. I check the temperature regularly as heat mats and thermostats are both known to stop working.
I do hope your little guy is molting, I wish you the best. Resist the urge to peek, and just keep using your nose.

