Rattling California Kingsnake....

[Tigergenesis]

I had totally forgotten that kings will imitate rattlers and rattle their tails - that is until my new girl rattled at me today. I went in her quarantine cage to change her water and I thought I'd seen some urates. I moved very slowly, but she seems to have keen eyesight/awareness of me when I'm barely in the room. I heard this noise and looked over realizing that she was rattling her tale. Kind of neat to hear, but I hate the idea that I may have been stressing her.

I know how rattlesnakes develop their rattles - how is it that kings are able to rattle as well? Is it the same as rattlesnakes?

When I picked her up at the reptile show yesterday she was as docile as could be - even when I brought her home. The lady told me to watch out because she can be nippy at times, so I was impressed/glad when she didn't show any such behavior with me yesterday. I tried not to bother her after getting in her cage, but I'm wanting to know how I should handle/approach her when she rattles at me - just ignore it and not back off? I'm not afraid of getting bit (I'm sure I'm bound to get bit one day by one of my snakes), but I'm more concerned about stressing her out. Any suggestions are appreciated. Thanks!