Okey, got it now. It was pretty much luck. :)
Okay, nice. :P
There is a tell, just very very subtle.
Also, I've got one more question: were there any enemies in that room when your entered it for the first time? If you remember.
Yes, there were two 'crabs'. Killed them before taking the picture. :)
Ah okay, good. That was the suspicious thing I noticed earlier. Killing one of them like that is kind of a bug I guess, but I just haven't found a good way to fix it yet. ;)