It is possible that they have a pending sentence in State that runs consecutively to the bid they are finishing up. Depending on their Judgement and Commitment document signed by the judge, their might be more time to be served
https://www.inmateaid.com/ask-the-inmate/why-would-they-send-someone-who-has-less-than-a-month-till-release-he-was-at-mcrp-in-la-back-to-state-and-will-he-now-have-to-serve-his-base-term#answer
Accepted Answer Date Created: February 01,2021