Blue Mushroom Issues?

I've got a fairly new Blue Mushroom (actinodiscus sp. I think) that over the last few days, seemed to be recovering from the stress of moving to my tank. It was starting to open up, It's been here for about 4 days. Tonight after lights out, I took a look at it and there was some stringy white/brown stuff coming out of the center. Whatever it was, the my peppermint shrimp was really interested in it. Later the mushroom didn't shrink, but it sort of closed around itself like a bell.

Last time I checked my parameters a few days ago, everything was fine, ie. no ammonia nitrite or nitrate, pH was 8, alkalinity was 11, calcium was a bit high at 550 or so. I'll test the water tomorrow if this is a negative stress reaction. The only thing that changed was that I added a few more snails and a couple hermit crabs last night, and this afternoon I dislodged a little bit of diatom algae that was on a bit of the sand and rock.

Should I be worried? Is this normal?

Sounds normal to me me as well. I have dozens of them in my tank and when they get stressed they pout for a few day before they start looking good again.