I have juz got tis budgie..she or he,is already tame wit me...?

but the body is so shaking..i wonder why...i don't think she or he is cold..cos i put the budgie in my room..or is the budgie still young..??? or scare..i don't tink the budgie is scare..i even put the bugie no my shoulder carry along anywhere..already tame..help anyone?.. make me scare what can i do????