behavioral thing

i've had Monty (BP) for about 3 months now he's my first herp
i noticed something just recently about him though and i was wondering if its just him or if all BP's do this

right before he strikes at something (whether its me or a mouse) his head starts quivering and its like a charge up if he doesn't get a full like 2 seconds of head quivering without the target moving he won't strike which has saved me from getting nailed by him a couple times.

They do line up their prey before the strike at it. You would too if you had to be accurate while hitting something as fast as they do...if they weren't that fast, rodents would be dining on snakes left and right.

I notice something like that with Pelota. Never thought of it as a head shaking thing. She seems to get in the S position and squirm in place as if to get herself comfy for the strike, then BAM its gone. She's only striked at me once though, and it was more of a feeding response thing. She smelled rodent in the air, and I was taking her out to lay down newspaper over her substrate. She seen the warmth of my face, smelled rodent, and took a quick strike. I was holding her too far away to hit me though, lol. It was too fast for me to notice the head quivering thing then. Tonight however, she was crawling all over me and flicking around my face, and I was watching her. Her head was sorta shaking a bit. Sorta like someone shakes when nervous. Never thought it was anything to do with striking, since she's such a laid back bp, lol.

Issa does the head quiver thing. He doesn't do it for very long, but he's definately going for it once he pulls the S curve.

Orpheus starts breathing real fast and right before he strikes holds his breath. He also does this forward and back thing with his head like the way a Chameleon walks.