What's going on with my birdsnests?

[RyanHounshell]

My birdsnests were doing really awesome and were growing like crazy. I left for 2 days and I came home to them all closed up. My other acros are wide open.
I did a water change before I left, the same day I do it every week. I'm super confused and would like to see if anyone else has ever had this problem.

 

[revhtree Verified Admin]

You have several of them closed up? Do you see anything picking at them?