The ghost owl...

A few nights ago I awoke from a deep sleep, groggily looked around my room, and found a pair of menacing dark orange eyes staring at me from outside my window.  After a few moments it faded away. My initial thought was that I must be imagining it but when I cleared my eyes and looked again the eyes had returned, yet again they only lasted a second before they disappeared. After a few more repetitions of the disappearing and reappearing eyes occurring at regular intervals I decided it must be caused by a reflection in the window from a light in my room. So I jumped up and looked around. Immediately when I stood up the eyes disappeared yet no lights were pointed at the window so I sat, pondering for a second.