As long as it hasnt been out too long its generally fine. Next time u thaw it out.... i wouldnt refreeze. keep in mind everytime you refreeze and thaw it out it breaks down the mouse/rat. So yes it may not be as "nutritious" for the snake.. but its just one not so nutritious meal. Better then tossing em out.
Me i have a few non feeders. i thaw out.. try to feed them first if no go i give it to another instead of thawing 2 out and one not eating