I've been bitten by a BP that was already out of the enclosure, but she was nervous and hungry and I hadn't been paying attention to her body language and where my arm was. Tali's never bitten me, but I've/something has startled her during handling so she coiled back into the 'S' shape for a few seconds before relaxing and going back to checking stuff out. I've waved my hand in front of her a couple of times when she's like that to see if she would strike (because I'd rather get a 'you were being stupid' bite then not knowing what it looked like and it be someone else), and she's never struck, but probably if I pushed her she might.
From what I've seen/heard, most strikes come with warnings- the s shape, tense body, agitated movement so if it's not doing that you are most likely fine and if it does, you are still most likely fine, just be cautious I guess? If the snakes I've handled seemed not happy, I rotate them away from my face and other people so if they do decide to snap at something, it's open air and not me.