Leather shedding

That is normal for some corals and is just their natural way of removing algae and detritus that may have accumulated on the coral.
As mentioned, a different position within the tank or increased flow should help, but nothing to really worry about. If it were melting or had a cheesy sonsistency to it then it would be reason for concern, but doesn't seem so in this case.

 

I've had mine for about 6 months, (devils finger) and it's never extended it's polpys. It has shedded countless times and I've never seen any polyps. Some say they take a while, a couple weeks sometimes after putting them into the take to extend polyps, well, I guess mine is different. I know yours isn't a devils finger but it's still a leather. My toadstool leathers are werid, they don't shed much and some days have polyps out, some days they don't.