Zoas and Duncan not opening up?

[reeferboy83]

I have about a 10 head duncan and some zoas on a rock that I have had in my tank for about 2 months. Here within the last week or so they will not open up all the way. Everything else in my tank including several pieces of Acro and other SPS and several other softies are doing good. All my params are in good order...Alk may be a little on the low side at 8. Any ideas on why these two pieces of coral would not be opening up all the way? They use to be fully extended.
Thanks