Possibility that you may have startled it. Don't worry though, it'll be fine. I remember when I was misting my male BP's enclosure and I had him in one hand and the other hand was misting the tank with a spray bottle and he struck at my other hand because maybe he found that to be a threat and I admit I was misting the enclosure quite fast just to get it over with. Sometimes he still gives me that "wtf" look and stares at me, so I will never put my hand in his face just in case lol. I know I can put my hand in my female BP's face though, she does not care if I do so.