This probably is not quite the same thing.
My thighs used to tremble whilst my teacher had me on the table, she
made very subtle "hand" suggestions and my knees responded by a
combination of resistance and trembling.
She asked why my legs trembled and I said something that indicated
that my level of control of my legs was simply too crude to follow her
subtle movements and suggestions.( People sometimes show a similar
thing when they try and thread a needle but feel they lack the fine
level of precision and control required, it can feel quite
frustrating).
My teacher then asked me why was I trying to control my legs when she
had asked me to leave them alone and not to help her !!!!!
It took an instant to absorb this information but actually a little
while to put it into practise, when I did the trembling stopped.
Regards Jon
The shaking is quite common. I've had it. I think it's probably to do with
you letting go of a habit that's been "in charge" for a long time. For a
short while there are two habits trying to control the same part of you, and
that can result in shaking.
My opinion only. If you're worried, I think it would be fine to call your
teacher between lessons.
Nick (AT teacher, UK)