HELP!!! Bubble Coral not opening....

[nc2tarheels]

I have a 12g Nano DLX and I have a small bubble coral. Well the past 3-4 days it hasn't opened at all. I've had this thing for about 3-4 monthes with no problems at all. I tested everything and all is well.

ph-8.4
trates-0
trites-0
ammonia-0
calcium-good
salinity 1.23-1.24
temp-83

 

[nmprisons]

is it in the same location it has always been? have you replaced the lights on your DLX recently? could something (a fish or a coral or an invert.) be irritating it?