When Aaron Hernandez said goodbye to Bristol County Jail ... it wasn't forever ... because he'll locked up there again soon ... so says Bristol County Sheriff Thomas Hodgson.
As we previously reported, Hernandez was transferred from BCJ to Suffolk County Jail this week -- claiming he felt he became a target in Bristol after he was accused of threatening to kill a guard.
He also claimed the move to Suffolk wuold be easier on his Boston-based lawyers.
TMZ Sports spoke with Sheriff Hodgson who tells us he has "no hard feelings" toward Hernandez -- and even said goodbye before he left -- but says he'll be back in his jail soon enough.
Hodgson says he expects AH to be transferred BACK to Bristol County Jail once the Odin Lloyd murder trial begins -- because that's where the court typically houses incarcerated defendants.
As for Aaaron, he's currently in gen pop at Suffolk County Jail -- while officials at his new home evaluate the safety situation to decide if he should be placed in an isolated part of the jail.
Stay tuned ...