Is there something wrong with my emperor angelfish?

[i love fish]

I've had my juvinile emperor for 5 months and every night she goes 2 sleep at the same time (no matter what, even if I go out and the lights r still on she knows it's dark outside) and at the same place.
Last night she didn't, she was up until late, and did not sleep in her 'bed', she slept in her hiding place when she's scared.
This morning she got up the usual time and ate and looks healthy and fine, acting normal as usual.
Any idea y she did this last night? Should I b concerned?

thanks

 

[tizzo]

ummm... I'm gonna guess and say no.
Maybe she just felt like a change of atmosphere would be good. I sleep on the couch for that very same reason.